v2.13.7

This reverts commit 9cf1c62147.

.gitignore

@@ -10,3 +10,4 @@ test/tmp
 /runtime.js
 coverage
 dist
+.package.json

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "vendor/regenerator"]
 	path = vendor/regenerator
 	url = https://github.com/facebook/regenerator
+[submodule "vendor/test262"]
+	path = vendor/test262
+	url = https://github.com/tc39/test262

.jshintrc

@@ -5,7 +5,6 @@
   "camelcase": true,
   "unused": true,
   "eqnull": true,
-  "proto": true,
   "newcap": true,
   "supernew": true,
   "noyield": true,
@@ -14,8 +13,6 @@
   "boss": true,
   "expr": true,
   "undef": true,
-  "loopfunc": true,
-  "white": true,
   "maxparams": 5,
   "maxdepth": 4,
 

.npmignore

@@ -9,3 +9,6 @@ Makefile
 dist
 tests.json
 CHANGELOG.md
+.package.json
+coverage
+vendor

.travis.yml

@@ -1,3 +1,4 @@
+sudo: false
 language: node_js
 node_js:
   - "0.10"

CHANGELOG.md

@@ -7,25 +7,289 @@
 > - [Breaking Change]
 > - [Documentation]
 > - [Internal]
-> - [Misc]
+> - [Polish]
 
 _Note: Gaps between patch versions are faulty/broken releases._
 
+## 2.13.7
+
+ * **Bug Fix**
+  * Don't realias variables that are already declared in optional `coreAliasing` transformer.
+
+## 2.13.6
+
+ * **Bug Fix**
+  * Add `NewExpression` as a valid parent for parentheses insertion for `ConditionalExpression`.
+
+## 2.13.5
+
+ * **Bug Fix**
+  * Allow rest parameters to be destructuring patterns.
+ * **Internal**
+  * Upgrade `kexec` to `1.1.0`.
+
+## 2.13.4
+
+ * **Bug Fix**
+  * Fix ordering of destructuring and default params.
+  * Fix loop body scope.
+  * Fix `for...of` transformation not retaining it's scope.
+  * Add destructuring assignment support to scope tracking.
+ * **Polish**
+  * More reliable newlines for pretty printing variable declarations.
+
+## 2.13.3
+
+ * **Internal**
+  * Add `coverage` and `vendor` to npmignore.
+
+## 2.13.2
+
+ * **Bug Fix**
+  * Fix `super` inside of nested functions.
+ * **Internal**
+  * Move let scoping TDZ into a separate transformer until it's more solid.
+  * Use `process.stdin.write` instead of `console.log` in `bin` to avoid sprintfification.
+
+## 2.13.1
+
+ * **New Feature**
+  * Temporal dead zone for block binding.
+
+## 2.13.0
+
+ * **New Feature**
+  * Block scoped functions.
+  * Add `--loose all` option.
+  * Add playground mallet operator thanks to [@jridgewell](https://github.com/jridgewell).
+ * **Bug Fix**
+  * Rewrote large parts of the let scoping transformer. Now passes all known tests.
+ * **Internal**
+  * Even more optimisations thanks to the awesome [@gaearon](https://github.com/gaearon).
+  * Upgrade `acorn-6to5`.
+    * Fixes exponentation operator thanks to [@charliesome](https://github.com/charliesome).
+    * Fix flow optional parameters with types.
+  * Upgrade `chokidar` to `0.12.6`.
+  * Upgrade `commander` to `2.6.0`.
+  * Upgrade `core-js` to `0.4.5`.
+  * Upgrade `estraverse` to `1.9.1`.
+  * Upgrade `jshint` to `2.5.11`.
+  * Upgrade `regenerator` to `0.8.9`.
+  * Upgrade `regexpu` to `1.0.0`.
+  * Upgrade `source-map` to `0.1.43`.
+  * Upgrade `source-map-support` to `0.2.9`.
+  * Upgrade `browserify` to `8.1.1`.
+  * Upgrade `chai` to `1.10.0`.
+  * Upgrade `istanbul` to `0.3.5`.
+  * Upgrade `mocha` to `2.1.0`.
+  * Upgrade `uglify-js` to `2.4.16`.
+
+## 2.12.6
+
+ * **Bug Fix**
+  * Add missing flow type traversal keys.
+
+## 2.12.5
+
+ * **Internal**
+  * Fix incorrect `for...in` loop still causing `ember-script` issues.
+
+## 2.12.4
+
+ * **Polish**
+  * Rest parameters now allocate the array before populating.
+ * **Internal**
+  * `for...in` loops have been changed to optimised `for` loops - better performance and no enumeration of protoype keys.
+  * Parts of the code generator have now been optimised thanks to [gaearon](https://github.com/gaearon).
+
+## 2.12.3
+
+ * **Spec Compliancy**
+  * Optional `typeof` transformer checks for `undefined` before passing it to the helper.
+  * Class methods are now named.
+
+## 2.12.2
+
+ * **Internal**
+  * Exclude nodes in function parameters and catch clauses from `isReferenced` check.
+
+## 2.12.1
+
+ * **Internal**
+  * Add `.jsx` to list of allowed extensions.
+
+## 2.12.0
+
+ * **Bug Fix**
+  * Support non-string JSX literals.
+ * **New Feature**
+  * Loose mode for some transformers that enables non-spec behaviour.
+ * **Internal**
+  * Uglify `--mangle sort` has been added to the build script, cutting minified scripts in half.
+
+## 2.11.4
+
+ * **Internal**
+  * Make all dependency versions fixed.
+
+## 2.11.3
+
+ * **Bug Fix**
+  * Allow a string to be passed as the `optional` option.
+
+## 2.11.2
+
+ * **Bug Fix**
+  * Support esprima-style catch clause handlers.
+ * **Polish**
+  * Don't print a stacktrace for syntax errors in the CLI.
+
+## 2.11.1
+
+ * **Bug Fix**
+  * Remove stray `console.log` outputting debug code.
+  * Remove `Dict` from `coreAliasing`.
+
+## 2.11.0
+
+ * **Bug Fix**
+  * Fix unnecessary IIFE in default parameters on method calls.
+  * Add support for supers inside of closures.
+ * **New Feature**
+  * Add `--keep-module-id-extensions`/`keepModuleIdExtensions` option to keep extensions in module ids.
+ * **Polish**
+  * Special case single argument spread properties in `super` inside classes.
+  * Don't use a variable declaration for class declaration IFFE.
+  * Rename `inherits` helper parameters.
+  * `coreAliasing` transformer now aliases `Promise`, `Set`, `Map` and more. Thanks [@AluisioASG](https://github.com/AluisioASG).
+
+## 2.10.1
+
+ * **Internal**
+  * Upgrade `core-js` to `0.4.4`.
+ * **New Feature**
+  * Added `--include-regenerator` option to CLI and `includeRegenerator` option to API that includes the regenerator runtime if necessary.
+
+## 2.10.0
+
+ * **New Feature**
+  * Add `classesFastSuper` optional transformer that doesn't support parent getters and prototype changing.
+  * Add `forOfFast` transformer that speeds up `for...of` on arrays but produces more code.
+  * Add `--react-compat` to `bin/6to5`.
+ * **Spec Compliancy**
+  * Disallow setters without a single parameter.
+  * Add `configurable` and `writable` to defined properties.
+  * Use define instead of assignment for class methods.
+ * **Polish**
+  * Fix bin name in `6to5-node --help`.
+  * Fix shorthand `--whitelist` name in `bin/6to5`.
+ * **Internal**
+  * Hot code optimisation of traversal etc thanks to [gaearon](https://github.com/gaearon).
+
+## 2.9.4
+
+ * **Bug Fix**
+  * Support `UpdateExpression`s as `MemberExpression` objects.
+
+## 2.9.3
+
+ * **Bug Fix**
+  * Remove `exportsWildcard` helper in favor of `defaults`.
+
+## 2.9.2
+
+ * **Bug Fix**
+  * Pass `exports` to `exportWildcard` helper to allow for use inside the optional runtime.
+
+## 2.9.1
+
+ * **Bug Fix**
+  * Fix runtime generator breaking the helper inclusion loop.
+
+## 2.9.0
+
+ * **Internal**
+  * Upgrade `acorn-6to5`.
+    * Now supports destructuring shorthand properties.
+
+## 2.8.1
+
+ * **Bug Fix**
+  * Fix computed accessors on object literals.
+
+## 2.8.0
+
+ * **New Feature**
+  * Add `commonStrict`, `amdStrict` and `umdStrict` module formatters that remove `module.exports` interop assignment.
+  * Add `--indent` option to the 6to5 CLI.
+
+## 2.7.4
+
+ * **Polish**
+  * Inherit assignments from their declaration in destructuring.
+  * Properly align multi-declarator variable declarations.
+
+## 2.7.3
+
+ * **Polish**
+  * Indent and add newlines to `React.createElement` calls in `react` transformer.
+  * Remove `Object.assign` calls and replace it with an `extends` helper.
+
+## 2.7.1
+
+ * **New Feature**
+  * Expose `version` on browser and node API.
+ * **Internal**
+  * Upgrade `core-js` to 0.4.1
+
+## 2.7.0
+
+ * **Spec Compliancy**
+  * Disallow reassignments of imports.
+ * **New Feature**
+  * `reactCompat` option to enable pre-v0.12 react components.
+
+## 2.6.3
+
+ * **Bug Fix**
+  * Fix 2.6.0 regression caused by faulty export default from a source handling.
+
+## 2.6.2
+
+ * **Bug Fix**
+  * Fix rest parameter keys when on functions with params.
+
+## 2.6.1
+
+ * **Bug Fix**
+  * Fix rest parameter arguments key.
+
 ## 2.6.0
 
- * [Internal] Fix incorrect AST node `identifier("this")`.
- * [Spec Compliancy] Add `interopRequireWildcard` around wildcard imports and exports to handle non-object exports.
- * [Internal] Upgrade `acorn-6to5`.
- * [New Feature] Basic destructuring defaults
- * [New Feature] Add `.es` to list of supported extensions.
- * [New Feature] Add optional `typeofSymbol` transformer.
- * [Bug Fix] Better handling of number literal property keys.
- * [Bug Fix] [Internal] Better `toIdentifier` method that handles reserved words.
- * [Internal] Upgrade to `core-js` 4.0.0.
- * [Internal] Upgrade to `regenerator` 0.8.3.
- * [Bug Fix] Handle `NewExpression` paren insertion edegcases better.
- * [Spec Compliancy] Class inheritance now has a `function` or `null` type check.
- * [Misc] Move `"use strict";` to inside module bodies instead of at the top of the file.
+ * **Bug Fix**
+  * Better handling of number literal property keys.
+  * Handle `NewExpression` paren insertion edegcases better.
+ * **Internal**
+  * Fix incorrect AST node `identifier("this")`.
+  * Better `toIdentifier` method that handles reserved words.
+  * Upgrade `acorn-6to5`.
+    * Fix exponentiation operator precedence.
+    * Fix line terminators after async contextual keywords.
+    * Add semicolons as class elements inside of a class body.
+  * Upgrade to `core-js` 4.0.0.
+  * Upgrade to `regenerator` 0.8.3.
+    * Fix non-loop labeled statements.
+ * **New Feature**
+  * Basic destructuring defaults
+  * Add `.es` to list of supported extensions.
+  * Add optional `typeofSymbol` transformer.
+  * Use a `for` loop for rest parameters instead of `Array.prototype.slice`.
+ * **Polish**
+  * Move `"use strict";` to inside module bodies instead of at the top of the file.
+  * Better handling of dynamic imports.
+ * **Spec Compliancy**
+  * Class inheritance now has a `function` or `null` type check.
+  * Add `interopRequireWildcard` around wildcard imports and exports to handle non-object exports.
 
 ## 2.5.0
 

CONTRIBUTING.md

@@ -1,6 +1,20 @@
 # Contributing
 
-Before contributing, please read the [code of conduct](https://github.com/6to5/6to5/blob/master/CODE_OF_CONDUCT.md).
+Contributions are always welcome, no matter how large or small. Before contributing, please read the [code of conduct](https://github.com/6to5/6to5/blob/master/CODE_OF_CONDUCT.md).
+
+## Developing
+
+#### Workflow
+
+* Fork the repository
+* Clone your fork and change directory to it (`git clone git@github.com:yourUserName/6to5.git && cd 6to5`)
+* Install the project dependencies (`make bootstrap`)
+* Link your forked clone (`npm link`)
+* Develop your changes ensuring you're fetching updates from upstream often
+* Ensure the test are passing (`make test`)
+* Create new pull request explaining your proposed change or reference an issue in your commit message
+
+#### Code Standards
 
  * **General**
    * No ES6 syntax features or methods, exclusively ES5.

Makefile

@@ -1,12 +1,13 @@
 BROWSERIFY_CMD = node_modules/browserify/bin/cmd.js
 ISTANBUL_CMD = node_modules/istanbul/lib/cli.js cover
 UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs
+#UGLIFY_CMD = node_modules/uglify-js/bin/uglifyjs --mangle sort
 JSHINT_CMD = node_modules/jshint/bin/jshint
 MOCHA_CMD = node_modules/mocha/bin/_mocha
 
 export NODE_ENV = test
 
-.PHONY: clean test test-cov test-clean lint test-travis test-spec test-browser publish bench build bootstrap
+.PHONY: clean test test-cov test-clean lint test-travis test-simple test-all test-browser publish build bootstrap publish-core
 
 build:
 	mkdir -p dist
@@ -27,12 +28,8 @@ build:
 clean:
 	rm -rf coverage templates.json test/tmp dist
 
-bench:
-	npm install es6-transpiler traceur esnext es6now jstransform
-	node node_modules/matcha/bin/_matcha
-
 lint:
-	$(JSHINT_CMD) --reporter node_modules/jshint-stylish/stylish.js lib bin benchmark/index.js
+	$(JSHINT_CMD) --reporter node_modules/jshint-stylish/stylish.js lib bin
 
 test-clean:
 	rm -rf test/tmp
@@ -41,14 +38,23 @@ test: lint
 	$(MOCHA_CMD)
 	make test-clean
 
+test-simple:
+	# excludes test262
+	export SIMPLE_6TO5_TESTS=1
+	make test
+
+test-all:
+	# includes traceur, esnext, regenerator
+	export ALL_6TO5_TESTS=1
+	make test
+
 test-cov:
+	export SIMPLE_6TO5_TESTS=1
 	rm -rf coverage
 	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
 
-test-spec:
-	node $(ISTANBUL_CMD) $(MOCHA_CMD) -- --reporter spec
-
-test-travis: test-spec
+test-travis: bootstrap
+	node $(ISTANBUL_CMD) $(MOCHA_CMD) --
 	if test -n "$$CODECLIMATE_REPO_TOKEN"; then codeclimate < coverage/lcov.info; fi
 
 test-browser:
@@ -59,13 +65,19 @@ test-browser:
 	node $(BROWSERIFY_CMD) -e test/_browser.js >dist/6to5-test.js
 	rm -rf templates.json tests.json
 
-	test -n "`which open`" && open test/browser.html
+	if [ -n $$BROWSER ]; then $$BROWSER test/browser.html; \
+	elif which xdg-open > /dev/null; then xdg-open 'test/browser.html'; \
+	elif which gnome-open > /dev/null; then gnome-open 'test/browser.html'; \
+	elif which open > /dev/null; then open 'test/browser.html'; fi \
 
 publish:
 	git pull --rebase
 
 	make test
 
+	read -p "Version: " version; \
+	npm version $$version --message "v%s"
+
 	make build
 	cp dist/6to5.min.js browser.js
 	cp dist/polyfill.min.js browser-polyfill.js
@@ -74,12 +86,21 @@ publish:
 	node bin/cache-templates
 	test -f templates.json
 
-	read -p "Version: "  version; \
-  npm version $$version --message "v%s"
 	npm publish
 
 	git push --follow-tags
 
+	# generate
+	bin/generate-core-package-json >package2.json
+	mv package.json .package.json
+	mv package2.json package.json
+
+	npm publish
+
+	# restore
+	rm -rf package.json
+	mv .package.json package.json
+
 	rm -rf templates.json browser.js runtime.js browser-polyfill.js
 
 bootstrap:

NOTES.md

@@ -1,3 +1,14 @@
 # Notes
 
- * Wildcard exports/imports wont normalise if `export default` is a non-object.
+ * Wildcard exports/imports wont normalise if `export default` is a non-object. See [#224](https://github.com/6to5/6to5/issues/224).
+
+## 3.0.0 breaking changes
+
+ * Remove `allowImportExportEverywhere` option from acorn.
+ * Remove this shorthand from playground.
+ * Remove `super()` inside non-constructors - add descriptive error message.
+ * Split up ES5 getter/setter transforming and ES6 property methods into separate transformers.
+ * Add autoindentation.
+ * Move `super` transformation from classes into a separate transformer that also supports object expressions.
+ * Remove fast transformer backwards compatibility.
+ * Rename let scoping transformer to block scoping.

benchmark/fixtures/all.js

@@ -1,99 +0,0 @@
-var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-var obj = {};
-var foo = "foo";
-var bar = "bar";
-
-// constants
-const MULTIPLIER = 5;
-
-// classes
-class Foo {
-  constructor() {
-    this.foo = "bar";
-  }
-}
-
-class Bar extends Foo {
-  constructor() {
-    super();
-  }
-
-  // default parameters
-  go(foo = "bar", bar = "foo") {
-
-  }
-
-  // not supported by jstransform
-  //get foo() {
-  //  return this._foo;
-  //}
-  //set foo(val) {
-  //  this._foo = val + " foo!";
-  //}
-}
-
-// arrow functions
-arr.map(x => x * x);
-
-// block binding
-for (let key in arr) {
-  let val = arr[key];
-  console.log(key, val);
-}
-
-// computed property names
-obj = {
-  ["foo" + bar]: "foobar"
-};
-
-// destructuring
-var [a, [b], c, d] = ["hello", [", ", "junk"], ["world"]];
-console.log(a + b + c);
-
-// array comprehension
-// [for (i of [1, 2, 3]) i * i]; // not supported by es6now
-
-// for-of
-for (var i of [1, 2, 3]) {
-  console.log(i * i);
-}
-
-// property method assignment
-obj = {
-  foo() {
-    return "foobar";
-  },
-
-  get bar() {
-    return this._bar;
-  },
-
-  set bar(val) {
-    this._bar = val;
-  }
-};
-
-// property name shorthand
-function f(x, y) {
-  return { x, y };
-}
-
-// rest parameters
-function printList(name, ...items) {
-  console.log("list %s has the following items", name);
-  items.forEach(function (item) {
-    console.log(item);
-  });
-}
-
-// spread
-function add(x, y) {
-  return x + y;
-}
-var numbers = [5, 10];
-add(...numbers);
-
-// template literals
-var x = 5;
-var y = 10;
-console.log(`${x} + ${y} = ${x + y}`);

benchmark/index.js

@@ -1,168 +0,0 @@
-Error.stackTraceLimit = Infinity;
-
-var jsTrans = require("jstransform");
-var traceur = require("traceur");
-//var es6tr   = require("es6-transpiler");
-var es6now  = require("es6now");
-//var esnext  = require("esnext");
-var to5     = require("../lib/6to5");
-
-//var uglify  = require("uglify-js");
-var matcha  = require("matcha");
-var path    = require("path");
-var fs      = require("fs");
-var _       = require("lodash");
-
-var readResolve = function (filename) {
-  try {
-    filename = require.resolve(filename);
-  } catch (err) {
-    return null;
-  }
-  return fs.readFileSync(filename, "utf8");
-};
-
-var getVersion = function (name) {
-  return require(name + "/package.json").version;
-};
-
-var jsTransVisitors = [];
-
-_.each([
-  "arrow-function-visitors", "class-visitors", "destructuring-visitors",
-  "object-concise-method-visitors", "object-short-notation-visitors",
-  "rest-param-visitors", "template-visitors"
-], function (name) {
-  var mod = require("jstransform/visitors/es6-" + name);
-  jsTransVisitors = jsTransVisitors.concat(mod.visitorList);
-});
-
-
-var compilers = {
-  "6to5": {
-    version: getVersion(".."),
-    compile: function (code, filename) {
-      return to5.transform(code, { filename: filename }).code;
-    }
-  },
-
-  traceur: {
-    runtime: readResolve("traceur/bin/traceur-runtime.js"),
-    compile: function (code) {
-      return traceur.compile(code, {
-        modules: "commonjs",
-        experimental: true
-      });
-    }
-  },
-
-  /*esnext: {
-    runtime: readResolve("esnext/node_modules/regenerator/runtime.js") || readResolve("regenerator/runtime.js"),
-    compile: function (code) {
-      return esnext.compile(code).code;
-    }
-  },*/
-
-  es6now: {
-    runtime: readResolve("es6now/runtime/ES6.js"),
-    compile: function (code) {
-      return es6now.translate(code);
-    }
-  },
-
-  /*"es6-transpiler": {
-    compile: function (code) {
-      var result = es6tr.run({ src: code });
-      if (result.errors.length) throw new Error(result.join("; "));
-      return result.src;
-    }
-  },*/
-
-  jstransform: {
-    compile: function (code) {
-      return jsTrans.transform(jsTransVisitors, code).code;
-    }
-  }
-};
-
-// versions
-
-//var uglifyTitle = "uglify v" + getVersion("uglify-js");
-
-_.each(compilers, function (compiler, name) {
-  compiler.title = name + " v" + (compiler.version || getVersion(name));
-});
-
-//
-
-var sizeBenchmark = function (code, loc, name, compiler) {
-  var log = function (output, title) {
-    title = [compiler.title].concat(title || []).join(" + ");
-
-    var text;
-    var color;
-    if (output.stack) {
-      text = "error";
-      color = "red";
-    } else {
-      var kilo  = (output.length / 1024).toFixed(2);
-      text = kilo + "KB";
-      color = "cyan";
-    }
-
-    text = matcha.utils.color(matcha.utils.padBefore(text, 22), color);
-
-    console.log(text, matcha.utils.color("» " + title, "gray"));
-
-    if (output.stack) {
-      console.error(output.stack);
-    }
-  };
-
-  var go = function (getOutput, title) {
-    var code;
-    try {
-      code = getOutput();
-    } catch (err) {
-      log(err, title);
-      return;
-    }
-
-    log(code, title);
-  };
-
-  var output;
-  go(function () {
-    return output = compiler.compile(code, loc);
-  });
-  if (!output) return;
-
-  //go(function () {
-  //  return uglify.minify(output, { fromString: true }).code;
-  //}, uglifyTitle);
-};
-
-//
-
-_.each(fs.readdirSync(__dirname + "/fixtures"), function (name) {
-  var alias = path.basename(name, path.extname(name));
-
-  suite(alias, function () {
-    set("delay", 0);
-
-    var loc  = __dirname + "/fixtures/" + name;
-    var code = fs.readFileSync(loc, "utf8");
-
-    before(function () {
-      _.each(compilers, function (compiler, name) {
-        sizeBenchmark(code, loc, name, compiler);
-      });
-    });
-
-    _.each(compilers, function (compiler) {
-      bench(compiler.title, function () {
-        compiler.compile(code, loc);
-      });
-    });
-  });
-});

bin/6to5/dir.js

@@ -1,9 +1,9 @@
-var chokidar = require("chokidar");
-var mkdirp   = require("mkdirp");
-var path     = require("path");
-var util     = require("./util");
-var fs       = require("fs");
-var _        = require("lodash");
+var outputFileSync = require("output-file-sync");
+var chokidar       = require("chokidar");
+var path           = require("path");
+var util           = require("./util");
+var fs             = require("fs");
+var _              = require("lodash");
 
 module.exports = function (commander, filenames, opts) {
   if (commander.sourceMapsInline) {
@@ -15,16 +15,13 @@ module.exports = function (commander, filenames, opts) {
 
     var data = util.compile(src, { sourceMapName: dest });
 
-    var up = path.normalize(dest + "/..");
-    mkdirp.sync(up);
-
     if (commander.sourceMaps) {
       var mapLoc = dest + ".map";
       data.code = util.addSourceMappingUrl(data.code, mapLoc);
-      fs.writeFileSync(mapLoc, JSON.stringify(data.map));
+      outputFileSync(mapLoc, JSON.stringify(data.map));
     }
 
-    fs.writeFileSync(dest, data.code);
+    outputFileSync(dest, data.code);
 
     console.log(src + " -> " + dest);
   };

bin/6to5/file.js

@@ -28,7 +28,7 @@ module.exports = function (commander, filenames) {
         map.setSourceContent(filename, result.actual);
 
         consumer.eachMapping(function (mapping) {
-          map._mappings.push({
+          map._mappings.add({
             generatedLine: mapping.generatedLine + offset,
             generatedColumn: mapping.generatedColumn,
             originalLine: mapping.originalLine,
@@ -63,7 +63,7 @@ module.exports = function (commander, filenames) {
 
       fs.writeFileSync(commander.outFile, result.code);
     } else {
-      console.log(result.code);
+      process.stdout.write(result.code + "\n");
     }
   };
 

bin/6to5/index.js

@@ -15,27 +15,29 @@ commander.option("-e, --experimental", "Enable experimental support for proposed
 commander.option("-p, --playground", "Enable playground support");
 
 commander.option("-m, --modules [modules]", "Module formatter type to use [common]", "common");
-commander.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
+commander.option("-l, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util.list);
 commander.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util.list);
 commander.option("-i, --optional [list]", "List of optional transformers to enable", util.list);
+commander.option("--loose [list]", "List of transformers to enable their loose mode", util.list);
 commander.option("-o, --out-file [out]", "Compile all input files into a single file");
 commander.option("-d, --out-dir [out]", "Compile an input directory of modules into an output directory");
 commander.option("-c, --remove-comments", "Remove comments from the compiled code", false);
+commander.option("-I, --indent [width]", "Indent width [2]", 2);
 commander.option("-a, --amd-module-ids", "Insert module id in AMD modules", false); // todo: remove in 3.0.0
 commander.option("-m, --module-ids", "Insert module id in modules", false);
+commander.option("-R, --react-compat", "Makes the react transformer produce pre-v0.12 code");
+commander.option("-E, --include-regenerator", "Include the regenerator runtime if necessary", false);
+commander.option("--keep-module-id-extensions", "Keep extensions when generating module ids", false);
 
 commander.on("--help", function(){
   var outKeys = function (title, obj) {
     console.log("  " + title + ":");
     console.log();
 
-    var hasOptional = true;
-
     _.each(_.keys(obj).sort(), function (key) {
       if (key[0] === "_") return;
 
       if (obj[key].optional) {
-        hasOptional = true;
         key = "[" + key + "]";
       }
 
@@ -98,17 +100,26 @@ if (errors.length) {
 //
 
 exports.opts = {
-  sourceMapName: commander.outFile,
-  experimental:  commander.experimental,
-  playground:    commander.playground,
-  moduleIds:     commander.amdModuleIds || commander.moduleIds,
-  blacklist:     commander.blacklist,
-  whitelist:     commander.whitelist,
-  sourceMap:     commander.sourceMaps || commander.sourceMapsInline,
-  optional:      commander.optional,
-  comments:      !commander.removeComments,
-  runtime:       commander.runtime,
-  modules:       commander.modules
+  keepModuleIdExtensions: commander.keepModuleIdExtensions,
+  includeRegenerator:     commander.includeRegenerator,
+  sourceMapName:          commander.outFile,
+  experimental:           commander.experimental,
+  reactCompat:            commander.reactCompat,
+  playground:             commander.playground,
+  moduleIds:              commander.amdModuleIds || commander.moduleIds,
+  blacklist:              commander.blacklist,
+  whitelist:              commander.whitelist,
+  sourceMap:              commander.sourceMaps || commander.sourceMapsInline,
+  optional:               commander.optional,
+  comments:               !commander.removeComments,
+  runtime:                commander.runtime,
+  modules:                commander.modules,
+  loose:                  commander.loose,
+  format: {
+    indent: {
+      style:     util.repeat(parseInt(commander.indent))
+    }
+  }
 };
 
 var fn;

bin/6to5/util.js

@@ -20,7 +20,17 @@ exports.transform = function (filename, code, opts) {
   opts = _.extend(opts || {}, index.opts);
   opts.filename = filename;
 
-  var result = to5.transform(code, opts);
+  var result;
+  try {
+    result = to5.transform(code, opts);
+  } catch (e) {
+    if (e instanceof SyntaxError) {
+      console.error("SyntaxError:", e.message);
+      process.exit(1);
+    } else {
+      throw e;
+    }
+  }
   result.filename = filename;
   result.actual = code;
   return result;

bin/_6to5-node

@@ -10,29 +10,31 @@ var util       = require("../lib/6to5/util");
 var vm         = require("vm");
 var _          = require("lodash");
 
-commander.option("-e, --eval [script]", "Evaluate script");
-commander.option("-p, --print", "Evaluate script and print result");
-commander.option("-i, --ignore [regex]", "Ignore all files that match this regex when using the require hook");
-commander.option("-x, --extensions [extensions]", "List of extensions to hook into [.es6,.js]");
-commander.option("-r, --experimental", "Enable experimental support for proposed ES7 features");
-commander.option("-g, --playground", "Enable playground support");
-commander.option("-c, --cache", "Cache compiled files and require paths");
+var program = new commander.Command("6to5-node");
+
+program.option("-e, --eval [script]", "Evaluate script");
+program.option("-p, --print", "Evaluate script and print result");
+program.option("-i, --ignore [regex]", "Ignore all files that match this regex when using the require hook");
+program.option("-x, --extensions [extensions]", "List of extensions to hook into [.es6,.js]");
+program.option("-r, --experimental", "Enable experimental support for proposed ES7 features");
+program.option("-g, --playground", "Enable playground support");
+program.option("-c, --cache", "Cache compiled files and require paths");
 
 var pkg = require("../package.json");
-commander.version(pkg.version);
-commander.usage("[options] [ -e script | script.js ] [arguments]");
-commander.parse(process.argv);
+program.version(pkg.version);
+program.usage("[options] [ -e script | script.js ] [arguments]");
+program.parse(process.argv);
 
-if (commander.cache) roadrunner.load();
+if (program.cache) roadrunner.load();
 
 //
 
 to5.register({
-  experimental: commander.experimental,
-  extensions:   commander.extensions,
-  playground:   commander.playground,
-  ignore:       commander.ignore,
-  cache:        commander.cache && roadrunner.get("6to5")
+  experimental: program.experimental,
+  extensions:   program.extensions,
+  playground:   program.playground,
+  ignore:       program.ignore,
+  cache:        program.cache && roadrunner.get("6to5")
 });
 
 //
@@ -41,17 +43,17 @@ var _eval = function (code, filename) {
   code = to5.transform(code, {
     filename: filename,
     blacklist: ["useStrict"],
-    experimental: commander.experimental,
-    playground: commander.playground
+    experimental: program.experimental,
+    playground: program.playground
   }).code;
   return vm.runInThisContext(code, filename);
 };
 
-if (commander.eval) {
-  var result = _eval(commander.eval, "eval");
-  if (commander.print) console.log(result);
+if (program.eval) {
+  var result = _eval(program.eval, "eval");
+  if (program.print) console.log(result);
 } else {
-  if (commander.args.length) {
+  if (program.args.length) {
     // slice all arguments up to the first filename since they're 6to5 args that we handle
     var args = process.argv.slice(2);
 
@@ -77,7 +79,7 @@ if (commander.eval) {
   }
 }
 
-if (commander.cache) roadrunner.save();
+if (program.cache) roadrunner.save();
 
 function replStart() {
   repl.start({
@@ -94,8 +96,8 @@ function replEval(code, context, filename, callback) {
   var result;
 
   try {
-    if (/^\((.*?)\n\)$/.test(code)) {
-      code = code.slice(1, -2); // remove "(" and "\n)"
+    if (code[0] === "(" && code[code.length - 1] === ")") {
+      code = code.slice(1, -1); // remove "(" and ")"
     }
 
     result = _eval(code, filename);

bin/generate-core-package-json

@@ -0,0 +1,11 @@
+#!/usr/bin/env node
+
+var pkg = require("../package.json");
+pkg.name += "-core";
+delete pkg.dependencies.chokidar;
+delete pkg.optionalDependencies;
+delete pkg.devDependencies;
+delete pkg.preferGlobal;
+delete pkg.scripts;
+delete pkg.bin;
+console.log(JSON.stringify(pkg, null, "  "));

doc/browser.md

@@ -1,65 +0,0 @@
-# Browser
-
-A browser version of 6to5 is available from `browser.js` inside the 6to5
-directory in an npm release.
-
-## Scripts
-
-While it's not recommended for serious use, when the browser version is included
-all scripts with the type `text/ecmascript-6` and `text/6to5` are automatically
-compiled and ran.
-
-For example:
-
-```html
-<script src="node_modules/6to5/browser.js"></script>
-<script type="text/6to5">
-class Test {
-  test() {
-    return "test";
-  }
-}
-
-var test = new Test;
-test.test();
-</script>
-```
-
-## Build
-
-You can build a browser version of the compiler by running the following in the
-6to5 directory:
-
-```sh
-$ make build
-```
-
-This will output the files `dist/6to5.js` and `dist/6to5.min.js`.
-
-## Test
-
-To test 6to5 in your browser run:
-
-```sh
-$ make test-browser
-```
-
-And open `test/browser.html` in your browser if it doesn't open automatically.
-
-## API
-
-### to5.transform(code, [opts])
-
-See [options](usage.md#options) for additional documentation.
-
-```javascript
-to5.transform("class Test {}").code;
-```
-
-### to5.run(code, [opts])
-
-See [options](usage.md#options) for additional documentation.
-
-```javascript
-to5.run("class Test {}");
-```

doc/caveats.md

@@ -1,62 +0,0 @@
-# Caveats
-
-In order for certain features to work they require certain polyfills. You can
-satisfy **all** 6to5 feature requirements by using the included
-[polyfill](polyfill.md).
-
-You may alternatively selectively include what you need:
-
-| Feature                     | Requirements                                                                                                           |
-| --------------------------- | ---------------------------------------------------------------------------------------------------------------------- |
-| Abstract References         | [experimental](experimental.md), `Symbol`                                                                              |
-| Array destructuring         | `Array.from`                                                                                                           |
-| Async functions, Generators | [experimental](experimental.md), [regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js) |
-| Comprehensions              | [experimental](experimental.md), `Array.from`                                                                          |
-| For Of                      | `Symbol`, `prototype[Symbol.iterator]`                                                                                 |
-| Modules                     | `Object.assign`*                                                                                                       |
-| Object spread/rest          | [experimental](experimental.md), `Object.assign`                                                                       |
-| Spread                      | `Array.from`                                                                                                           |
-
-*Only required for exporting a non-function `default` with additional `export`s.
-
-## ES5
-
-Since 6to5 assumes that your code will be ran in an ES5 environment it uses ES5
-functions. So if you're using an environment that has limited or no support for
-ES5 such as lower versions of IE then using the
-[es5-shim](https://github.com/es-shims/es5-shim) along with the
-[6to5 polyfill](polyfill.md) will add support for these methods.
-
-## Internet Explorer
-
-### Classes (10 and below)
-
-If you're inheriting from a class then static properties are inherited from it
-via [\_\_proto\_\_](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto),
-this is widely supported but you may run into problems with much older browsers.
-
-**NOTE:** `__proto__` is not supported in IE <= 10 so static properties
-**will not** be inherited. A possible workaround is to use `super();`:
-
-```javascript
-class Foo {
-  static foo() {
-
-  }
-}
-
-class Bar extends Foo {
-  static foo() {
-    super();
-  }
-}
-```
-
-## Getters/setters (8 and below)
-
-In IE8 `Object.defineProperty` can only be used on DOM objects. This is
-unfortunate as it's required to set getters and setters. Due to this if
-you plan on supporting IE8 or below then the user of getters and setters
-isn't recommended.
-
-**Reference**: [MDN](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty#Internet_Explorer_8_specific_notes).

doc/differences.md

@@ -1,137 +0,0 @@
-# Differences
-
-There are three main points that separate 6to5 from all other transpilers.
-
-### Readable code
-
-The fundamental concept behind 6to5 is that the generated code must be close as
-possible to the original, retaining all the same formatting and readability.
-
-Many other transpilers are just concerned with making the code work while 6to5
-is concerned with making sure it works **and** is readable at the same time.
-
-For example, given the following array comprehension:
-
-```javascript
-var seattlers = [for (c of customers) if (c.city == "Seattle") { name: c.name, age: c.age }];
-```
-
-is generated to the following with 6to5:
-
-```javascript
-var seattlers = Array.from(customers).filter(function (c) {
-  return c.city == "Seattle";
-}).map(function (c) {
-  return {
-    name: c.name,
-    age: c.age
-  };
-});
-```
-
-The following is what Traceur generates:
-
-```javascript
-var seattlers = (function() {
-  var c;
-  var $__20 = 0,
-      $__21 = [];
-  for (var $__22 = customers[$traceurRuntime.toProperty(Symbol.iterator)](),
-      $__23; !($__23 = $__22.next()).done; ) {
-    c = $__23.value;
-    if (c.city == "Seattle")
-      $traceurRuntime.setProperty($__21, $__20++, {
-        name: c.name,
-        age: c.age
-      });
-  }
-  return $__21;
-}());
-```
-
-As you can tell, it's not very pretty. Instead of mapping directly to a
-runtime, like other transpilers, 6to5 maps directly to the equivalent ES5.
-
-Sometimes there are little inline functions that 6to5 needs. These are
-placed at the top of your file much like coffee-script does. If these
-bother you then you can use the [optional runtime](optional-runtime.md).
-We promise that these inline functions will never be significant and will
-always be used as little as possible.
-
-### Static analysis
-
-6to5 uses a lot of static analysis to simplify code as much as possible.
-Not many other transpilers do this, and those that do don't do it nearly
-as much as 6to5. This process is pretty intensive but it leads to higher
-quality code.
-
-### Spec compliancy
-
-6to5 prides itself on
-[spec compliancy](https://kangax.github.io/compat-table/es6/). We have
-excellent support for edgecases, something that many other transpilers
-suffer from, including Traceur. When you use 6to5 you can be confident
-that when you turn it off and use your code in a full ES6 environment
-**it'll just work**.
-
-## Comparison to other transpilers
-
-### Features
-
-|                              | 6to5 | Traceur | es6-transpiler | es6now | jstransform |
-| ---------------------------- | ---- | ------- | -------------- | ------ | ----------- |
-| Source maps                  | ✓    | ✓       | ✓              |        | ✓           |
-| No compiler global pollution | ✓    |         | ✓              |        | ✓           |
-| Optional runtime             | ✓    |         | ✓              |        | ✓           |
-| Browser compiler             | ✓    | ✓       |                |        |             |
-
-### Language Support
-
-|                              | 6to5 | Traceur | es6-transpiler | es6now | jstransform |
-| ---------------------------- | ---- | ------- | -------------- | ------ | ----------- |
-| Abstract references          | ✓    |         |                |        |             |
-| Array comprehension          | ✓    | ✓       | ✓              |        |             |
-| Arrow functions              | ✓    | ✓       | ✓              | ✓      | ✓           |
-| Async functions              | ✓    | ✓       |                |        |             |
-| Async generator functions    | ✓    | ✓       |                |        |             |
-| Classes                      | ✓    | ✓       | ✓              | ✓      | ✓           |
-| Computed property names      | ✓    | ✓       | ✓              | ✓      |             |
-| Constants                    | ✓    | ✓       | ✓              |        |             |
-| Default parameters           | ✓    | ✓       | ✓              | ✓      |             |
-| Destructuring                | ✓    | ✓       | ✓              | ✓      | ✓           |
-| Exponentiation operator      | ✓    | ✓       |                |        |             |
-| Flow types                   | ✓    |         |                |        | ✓           |
-| For-of                       | ✓    | ✓       | ✓              | ✓      |             |
-| Generators                   | ✓    | ✓       |                |        |             |
-| Generator comprehension      | ✓    | ✓       |                |        |             |
-| JSX                          | ✓    |         |                |        |             |
-| Let scoping                  | ✓    | ✓       | ✓              |        |             |
-| Modules                      | ✓    | ✓       |                | ✓      |             |
-| Object rest/spread           | ✓    |         |                |        | ✓           |
-| Property method assignment   | ✓    | ✓       | ✓              | ✓      | ✓           |
-| Property name shorthand      | ✓    | ✓       | ✓              | ✓      | ✓           |
-| Rest parameters              | ✓    | ✓       | ✓              | ✓      | ✓           |
-| React                        | ✓    |         |                |        |             |
-| Spread                       | ✓    | ✓       | ✓              | ✓      |             |
-| Template literals            | ✓    | ✓       | ✓              | ✓      | ✓           |
-| Unicode regex                | ✓    | ✓       | ✓              |        |             |
-
-### [Traceur](https://github.com/google/traceur-compiler)
-
-Traceur requires quite a bulky runtime (~75KB) and produces quite verbose code.
-While this can be trimmed down by selectively building the runtime, it's an
-unnecessary step when a large runtime can be eliminated entirely.
-
-### [es6now](https://github.com/zenparsing/es6now)
-
-es6now doesn't output sourcemaps. This is cited as a positive as line-to-line
-mapping is the goal. This however obviously doesn't retain column mapping
-resulting in the output code not being very pleasant.
-
-### [es6-transpiler](https://github.com/termi/es6-transpiler)
-
-The es6-transpiler compiler requires shims to operate which pollutes the global
-scope resulting in possible collisions.
-
-es6-transpiler maps line-by-line, just like es6now, this results in the same
-issues such as lack of column information and unpleasant code output.

doc/experimental.md

@@ -1,8 +0,0 @@
-## Experimental
-
-6to5 also has experimental support for ES7 proposals. You can enable this with
-the `experimental: true` option when using the [Node API](#node) or
-`--experimental` when using the [CLI](#cli).
-
-**WARNING:** These proposals are subject to change so use with
-**extreme caution**.

doc/features.md

@@ -1,283 +0,0 @@
-# Features
-
-## Abstract references ([experimental](experimental.md)) ([spec](https://github.com/zenparsing/es-abstract-refs))
-
-```javascript
-foo::bar;
-foo::bar = baz;
-delete foo::bar;
-```
-
-## Array comprehensions ([experimental](experimental.md))
-
-```javascript
-var results = [for (c of customers) if (c.city == "Seattle") { name: c.name, age: c.age }]
-```
-
-## Arrow functions
-
-```javascript
-// Expression bodies
-var odds = evens.map(v => v + 1);
-var nums = evens.map((v, i) => v + i);
-
-// Statement bodies
-nums.forEach(v => {
-  if (v % 5 === 0)
-    fives.push(v);
-});
-
-// Lexical this
-var bob = {
-  _name: "Bob",
-  _friends: [],
-  printFriends() {
-    this._friends.forEach(f => {
-      console.log(this._name + " knows " + f);
-    });
-  }
-};
-```
-
-## Async functions ([experimental](experimental.md)) ([spec](https://github.com/lukehoban/ecmascript-asyncawait))
-
-```javascript
-async function chainAnimationsAsync(elem, animations) {
-  for (var anim of animations) {
-    await anim(elem);
-  }
-}
-```
-
-## Async generator functions ([experimental](experimental.md)) ([spec](https://github.com/jhusain/asyncgenerator))
-
-```javascript
-
-```
-
-## Classes
-
-```javascript
-class SkinnedMesh extends THREE.Mesh {
-  constructor(geometry, materials) {
-    super(geometry, materials);
-
-    this.idMatrix = SkinnedMesh.defaultMatrix();
-    this.bones = [];
-    this.boneMatrices = [];
-    //...
-  }
-
-  update(camera) {
-    //...
-    super.update();
-  }
-
-  static defaultMatrix() {
-    return new THREE.Matrix4();
-  }
-}
-```
-
-## Computed property names
-
-```javascript
-var foo = "foo";
-var bar = "bar";
-var obj = {
-  ["foo" + bar]: "heh",
-  ["bar" + foo]: "noo",
-  foo: "foo",
-  bar: "bar"
-};
-```
-
-## Constants
-
-```javascript
-const MULTIPLIER = 5;
-console.log(2 * MULTIPLIER);
-
-MULTIPLIER = 6; // error
-var MULTIPLIER; // error
-```
-
-## Default parameters
-
-```javascript
-function f(x, y = 12) {
-  // y is 12 if not passed (or passed as undefined)
-  return x + y;
-}
-f(3) == 15
-```
-
-## Destructuring
-
-```javascript
-// list matching
-var [a, , b] = [1,2,3];
-
-// object matching
-var { op: a, lhs: { op: b }, rhs: c } = getASTNode();
-
-// object matching shorthand
-// binds `op`, `lhs` and `rhs` in scope
-var { op, lhs, rhs } = getASTNode();
-
-// Can be used in parameter position
-function g({ name: x }) {
-  console.log(x);
-}
-g({ name: 5 });
-
-// Fail-soft destructuring
-var [a] = [];
-a === undefined;
-```
-
-## Exponentiation operator ([experimental](experimental.md)) ([spec](https://github.com/rwaldron/exponentiation-operator))
-
-```javascript
-var a = 2;
-a **= 2;
-
-var squared = 2 ** 2;
-```
-
-## For-of
-
-```javascript
-for (var i of [1, 2, 3]) {
-  console.log(i * i);
-}
-```
-
-## Generators
-
-```javascript
-function* fibonacci() {
-  var pre = 0, cur = 1;
-  for (;;) {
-    var temp = pre;
-    pre = cur;
-    cur += temp;
-    yield cur;
-  }
-}
-
-for (var n of fibonacci()) {
-  // truncate the sequence at 1000
-  if (n > 1000) break;
-  console.log(n);
-}
-```
-
-## Generator comprehensions ([experimental](experimental.md))
-
-```javascript
-var nums = [1, 2, 3, 4, 5, 6];
-var multiples = (for (i of nums) if (i % 2) i * i);
-assert.equal(multiples.next().value, 1);
-assert.equal(multiples.next().value, 9);
-assert.equal(multiples.next().value, 25);
-```
-
-## Let scoping
-
-```javascript
-for (let i in arr) {
-  let v = arr[i];
-}
-```
-
-## Modules
-
-```javascript
-import "foo";
-import foo from "foo";
-import * as foo from "foo";
-import {bar} from "foo";
-import {foo as bar} from "foo";
-
-export { test };
-export var test = 5;
-export function test() {}
-
-export default test;
-```
-
-## Numeric literals
-
-```javascript
-0b111110111 === 503; // true
-0o767 === 503; // true
-```
-
-## Object spread/rest ([experimental](experimental.md)) ([spec](https://github.com/sebmarkbage/ecmascript-rest-spread))
-
-```javascript
-var n = { x, y, ...z };
-var { x, y, ...z } = { x: 1, y: 2, a: 3, b: 4 };
-```
-
-## Property method assignment
-
-```javascript
-var obj = {
-  foo() {
-    return "foobar";
-  },
-
-  get bar() {
-    return this._bar;
-  },
-
-  set bar(val) {
-    this._bar = val;
-  }
-};
-```
-
-## Property name shorthand
-
-```javascript
-function f(x, y) {
-  return { x, y };
-}
-```
-
-## Rest parameters
-
-```javascript
-function f(x, ...y) {
-  // y is an Array
-  return x * y.length;
-}
-f(3, "hello", true) == 6
-```
-
-## Spread
-
-```javascript
-function f(x, y, z) {
-  return x + y + z;
-}
-// Pass each elem of array as argument
-f(...[1,2,3]) == 6
-```
-
-## Template literals
-
-```javascript
-var x = 5;
-var y = 10;
-console.log(`${x} + ${y} = ${x + y}`); // "5 + 10 = 15"
-```
-## Unicode regex
-
-```javascript
-var string = 'foo💩bar';
-var match = string.match(/foo(.)bar/u);
-console.log(match[1]);
-```

doc/index.md

@@ -1,62 +1 @@
-**6to5** turns ES6+ code into vanilla ES5, so you can use next generation features **today.**
-
- - **Readable** - formatting is retained if possible so your generated code is as similar as possible.
- - **Extensible** - with a large range of [plugins](plugins.md) and **browser support**.
- - **Lossless** - **source map support** so you can debug your compiled code with ease.
- - **Compact** - maps directly to the equivalent ES5 with **no runtime**[\*](caveats.md).
-
-## Installation
-
-It's as easy as:
-
-    $ npm install -g 6to5
-
-## Usage
-
-Once you've installed 6to5, there are multiple paths you can take depending on
-how you want to use it.
-
-6to5 will simply compile your ES6+ script to ES5 if you pass it as an argument
-to the command-line tool `6to5`:
-
-```sh
-$ 6to5 script.js
-```
-
-If you have a file written using ES6+ and you just want to run it, `6to5-node`
-has you covered:
-
-```sh
-$ 6to5-node script.js
-```
-
-And it doesn't end here! To see all the ways you can use 6to5, check out the
-[Usage](http://6to5.github.io/usage.html) page.
-
-## [Features](features.md)
-
- - [Abstract references](features.md#abstract-references) ([experimental](experimental.md))
- - [Array comprehension](features.md#array-comprehension) ([experimental](experimental.md))
- - [Async functions](features.md#async-functions) ([experimental](experimental.md))
- - [Async generator functions](features.md#async-generator-functions) ([experimental](experimental.md))
- - [Arrow functions](features.md#arrow-functions)
- - [Classes](features.md#classes)
- - [Computed property names](features.md#computed-property-names)
- - [Constants](features.md#constants)
- - [Default parameters](features.md#default-parameters)
- - [Destructuring](features.md#destructuring)
- - [Exponentiation operator](features.md#exponentiation-operator) ([experimental](experimental.md))
- - [For-of](features.md#for-of)
- - [Generators](features.md#generators)
- - [Generator comprehension](features.md#generator-comprehension) ([experimental](experimental.md))
- - [Let scoping](features.md#let-scoping)
- - [Modules](features.md#modules)
- - [Numeric literals](features.md#numeric-literals)
- - [Object rest/spread](features.md#object-rest-spread) ([experimental](experimental.md))
- - [Property method assignment](features.md#property-method-assignment)
- - [Property name shorthand](features.md#property-name-shorthand)
- - [React/JSX](react.md)
- - [Rest parameters](features.md#rest-parameters)
- - [Spread](features.md#spread)
- - [Template literals](features.md#template-literals)
- - [Unicode regex](features.md#unicode-regex)
+See [6to5.github.io/docs](https://github.com/6to5/6to5.github.io/tree/master/docs).

doc/modules.md

@@ -1,257 +0,0 @@
-# Modules
-
-## Usage
-
-### CLI
-
-```sh
-$ 6to5 --modules common script.js
-```
-
-### Node
-
-```javascript
-var to5 = require("6to5");
-to5.transform('import "foo";', { modules: "common" });
-```
-
-## Formats
-
- * [AMD](#amd)
- * [Common (Default)](#common-default)
- * [Ignore](#ignore)
- * [System](#system)
- * [UMD](#umd)
-
-### Common
-
-```sh
-$ 6to5 --modules common
-```
-
-**In**
-
-```javascript
-export default test;
-
-export {test};
-export var test = 5;
-
-import "foo";
-
-import foo from "foo";
-import * as foo from "foo";
-
-import {bar} from "foo";
-import {foo as bar} from "foo";
-```
-
-**Out**
-
-```javascript
-"use strict";
-
-var _interopRequire = function (obj) {
-  return obj && (obj["default"] || obj);
-};
-
-exports = module.exports = test;
-
-exports.test = test;
-var test = exports.test = 5;
-
-require("foo");
-
-var foo = _interopRequire(require("foo"));
-
-var foo = require("foo");
-
-var bar = require("foo").bar;
-var bar = require("foo").foo;
-```
-
-### AMD
-
-```sh
-$ 6to5 --modules amd
-```
-
-**In**
-
-```javascript
-import foo from "foo";
-
-export function bar() {
-  return foo("foobar");
-}
-```
-
-**Out**
-
-```javascript
-define(["exports", "foo"], function (exports, _foo) {
-  "use strict";
-
-  var _interopRequire = function (obj) {
-    return obj && (obj["default"] || obj);
-  };
-
-  exports.bar = bar;
-  var foo = _interopRequire(_foo);
-
-  function bar() {
-    return foo("foobar");
-  }
-});
-```
-
-You can optionally specify to include the module id (using the `--amd-module-id` argument):
-
-```javascript
-define("filename", ["exports", "foo"], function (exports, _foo) {})
-```
-
-### UMD
-
-```sh
-$ 6to5 --modules umd
-```
-
-**In**
-
-```javascript
-import foo from "foo";
-
-export function bar() {
-  return foo("foobar");
-}
-```
-
-**Out**
-
-```javascript
-(function (factory) {
-  if (typeof define === "function" && define.amd) {
-    define(["exports", "foo"], factory);
-  } else if (typeof exports !== "undefined") {
-    factory(exports, require("foo"));
-  }
-})(function (exports, _foo) {
-  "use strict";
-
-  var _interopRequire = function (obj) {
-    return obj && (obj["default"] || obj);
-  };
-
-  exports.bar = bar;
-  var foo = _interopRequire(_foo);
-
-  function bar() {
-    return foo("foobar");
-  }
-});
-```
-
-### Ignore
-
-```sh
-$ 6to5 --modules ignore
-```
-
-**In**
-
-```javascript
-import foo from "foo";
-
-export function bar() {
-  return foo("foobar");
-}
-```
-
-**Out**
-
-```javascript
-function bar() {
-  return foo("foobar");
-}
-```
-
-### System
-
-```sh
-$ 6to5 --modules system
-```
-
-**In**
-
-```javascript
-import foo from "foo";
-
-export function bar() {
-  return foo("foobar");
-}
-```
-
-**Out**
-
-```javascript
-System.register("bar", ["foo"], function (_export) {
-  "use strict";
-
-  var __moduleName = "bar";
-
-  var foo;
-  function bar() {
-    return foo("foobar");
-  }
-  return {
-    setters: [function (m) {
-      foo = m.default;
-    }],
-    execute: function () {
-      _export("bar", bar);
-    }
-  };
-});
-```
-
-## Custom
-
-You can alternatively specify module names instead of one of the built-in types.
-
-```sh
-$ 6to5 --modules custom-module-formatter
-```
-
-**node_modules/custom-module-formatter/index.js**
-
-```javascript
-module.exports = ModuleFormatter;
-
-function ModuleFormatter() {
-
-}
-
-ModuleFormatter.prototype.transform = function (ast) {
-  // this is ran after all transformers have had their turn at modifying the ast
-  // feel free to modify this however
-};
-
-ModuleFormatter.prototype.importDeclaration = function (node, nodes) {
-  // node is an ImportDeclaration
-};
-
-ModuleFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
-  // specifier is an ImportSpecifier
-  // node is an ImportDeclaration
-};
-
-ModuleFormatter.prototype.exportDeclaration = function (node, nodes) {
-  // node is an ExportDeclaration
-};
-
-ModuleFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
-  // specifier is an ExportSpecifier
-  // node is an ExportDeclaration
-};
-```

doc/optional-runtime.md

@@ -1,57 +0,0 @@
-# Optional runtime
-
-6to5 has a few helper functions that'll be placed at the top of the generated
-code if needed so it's not inlined multiple times throughout that file. This may
-become an issue if you have multiple files, especially when you're sending them
-to the browser. gzip alleviates most of this concern but it's still not ideal.
-
-You can tell 6to5 to not place any declarations at the top of your files and
-instead just point them to a reference contained within the runtime.
-
-Simply use the following option if you're using the [Node API](usage.md#node):
-
-```javascript
-{
-  runtime: true
-}
-```
-
-or the following flag if you're using the [CLI](usage.md#cli):
-
-```ssh
-$ 6to5 --runtime
-```
-
-Then just include the runtime before your generated code.
-
-## Getting the runtime
-
-You can get the runtime via either:
-
-```sh
-$ 6to5-runtime
-```
-
-or
-
-```javascript
-require("6to5").runtime();
-```
-
-or from an npm release in `runtime.js` from the 6to5 directory.
-
-## Customising namespace
-
-You can also customise the runtime namespace by passing an optional namespace
-argument:
-
-```javascript
-require("6to5").runtime("myCustomNamespace");
-```
-
-```sh
-$ 6to5-runtime myCustomNamespace
-```
-
-See [Options - runtime](usage.md#options) for documentation on changing the
-reference in generated code.

doc/playground.md

@@ -1,140 +0,0 @@
-# Playground
-
-Playground is a proving ground for **possible** ES7 proposals.
-
-**NOTE: These features are in no way endorsed by Ecma International and are not a part of ES6. They might become a part of ECMAScript in the future.**
-
-## Usage
-
-    $ 6to5 --playground
-
-```javascript
-to5.transform("code", { playground: true });
-```
-
-**NOTE:** Enabling `playground` also enables [experimental support](experimental.md).
-
-## Features
-
- * [Memoization operator](#memoization-operator)
- * [Method binding](#method-binding)
- * [Method binding function shorthand](#method-binding-function-shorthand)
- * [Object getter memoization](#object-getter-memoization)
- * [This shorthand](#this-shorthand)
-
-### Memoization assignment operator
-
-The memoization assignment operator allows you to lazily set an object property.
-It checks whether there's a property defined on the object and if there isn't then
-the right hand value is set.
-
-This means that `obj.x` in the following `var x = { x: undefined }; obj.x ?= 2;`
-will still be `undefined` because it's already been defined on the object.
-
-```javascript
-var obj = {};
-obj.x ?= 2;
-obj.x; // 2
-
-obj = { x: 1 };
-obj.x ?= 2;
-obj.x; // 1
-
-obj = { x: undefined }
-obj.x ?= 2;
-obj.x; // undefined
-```
-
-```javascript
-var obj = {};
-obj.x ?= 2;
-```
-
-equivalent to
-
-```javascript
-var obj = {};
-if (!Object.prototype.hasOwnProperty.call(obj, "x")) obj.x = 2;
-```
-
-### Method binding
-
-```javascript
-var fn = obj#method;
-var fn = obj#method("foob");
-```
-
-equivalent to
-
-```javascript
-var fn = obj.method.bind(obj);
-var fn = obj.method.bind(obj, "foob");
-```
-
-### Method binding function shorthand
-
-```javascript
-["foo", "bar"].map(#toUpperCase); // ["FOO", "BAR"]
-[1.1234, 23.53245, 3].map(#toFixed(2)); // ["1.12", "23.53", "3.00"]
-```
-
-equivalent to
-
-```javascript
-["foo", "bar"].map(function (val) { return val.toUpperCase(); });
-[1.1234, 23.53245, 3].map(function (val) { return val.toFixed(2); });
-```
-
-### Object getter memoization
-
-```javascript
-var foo = {
-  memo bar() {
-    return complex();
-  }
-};
-
-class Foo {
-  memo bar() {
-    return complex();
-  }
-}
-```
-
-equivalent to
-
-```javascript
-var foo = {
-  get bar() {
-    return Object.defineProperty(this, "bar", {
-      value: complex(),
-      enumerable: true,
-      configurable: true,
-      writable: true
-    }).bar;
-  }
-};
-
-class Foo {
-  get bar() {
-    return Object.defineProperty(this, "bar", {
-      value: complex(),
-      enumerable: true,
-      configurable: true,
-      writable: true
-    }).bar;
-  }
-}
-```
-
-### This shorthand
-
-```javascript
-@foo
-```
-
-equivalent to
-
-```javascirpt
-this.foo
-```

doc/plugins.md

@@ -1,33 +0,0 @@
-# Plugins
-
-## Build systems
-
- - [Broccoli](https://github.com/6to5/broccoli-6to5-transpiler)
- - [Browserify](https://github.com/6to5/6to5ify)
- - [Brunch](https://github.com/6to5/6to5-brunch)
- - [Duo](https://github.com/6to5/duo6to5)
- - [Gobble](https://github.com/6to5/gobble-6to5)
- - [Gulp](https://github.com/6to5/gulp-6to5)
- - [Grunt](https://github.com/6to5/grunt-6to5)
- - [Sprockets](https://github.com/josh/sprockets-es6) or via [Browserify](https://github.com/6to5/6to5-rails)
- - [webpack](https://github.com/6to5/6to5-loader)
-
-## Integrations
-
- - [Isparta](https://github.com/douglasduteil/isparta) - Code coverage with `karma` and `instanbul` using 6to5
- - [JSXHint](https://github.com/STRML/JSXHint) - A wrapper around JSHint to allow linting of JSX files
-
-## Bridges
-
- - [Ruby](https://github.com/6to5/6to5-ruby)
-
-## Testing
-
- - [Jest](https://github.com/6to5/6to5-jest)
- - [Karma](https://github.com/6to5/karma-6to5-preprocessor)
- - [Mocha](https://github.com/6to5/6to5-mocha)
-
-## Misc
-
- - [Connect](https://github.com/6to5/6to5-connect)
- - [Jade](https://github.com/6to5/jade-6to5)

doc/polyfill.md

@@ -1,34 +0,0 @@
-# Polyfill
-
-6to5 includes a polyfill that includes a custom
-[regenerator runtime](https://github.com/facebook/regenerator/blob/master/runtime.js) and
-[core.js](https://github.com/zloirock/core-js).
-
-This will emulate a full ES6 environment. This polyfill is automatically loaded
-when using [6to5-node](usage.md#node) and [6to5/register](usage.md#register-hook).
-
-## Usage
-
-### Node/Browserify
-
-You need to include the polyfill require at the top the **entry point** to your
-application.
-
-```javascript
-require("6to5/polyfill");
-```
-
-Fortunately, this is automatically loaded when using:
-
-```javascript
-require("6to5/register");
-```
-
-### Browser
-
-Available from the `browser-polyfill.js` file within the 6to5 directory of an
-npm release. This needs to be included **before** all your compiled 6to5 code.
-You can either prepend it to your compiled code or include it in a `<script>`
-before it.
-
-**NOTE:** Do not `require` this via browserify etc, use `6to5/polyfill`.

doc/react.md

@@ -1,17 +0,0 @@
-# React/JSX
-
-6to5 has built-in support for React v0.12. Tags are automatically transformed to
-their equivalent `React.createElement(...)` and `displayName` is automatically
-inferred and added to all `React.createClass` calls.
-
-## Blacklist
-
-To disable this behaviour add `react` to your blacklist:
-
-```javascript
-to5.transform("code", { blacklist: ["react"] });
-```
-
-```sh
-$ 6to5 --blacklist react
-```

doc/usage.md

@@ -1,259 +0,0 @@
-# Usage
-
-## CLI
-
-Compile the file `script.js` and output it to stdout.
-
-```sh
-$ 6to5 script.js
-```
-
-Compile the file `script.js` and output it to `script-compiled.js`.
-
-```sh
-$ 6to5 script.js --out-file script-compiled.js
-```
-
-Compile the file `script.js` and output it to `script-compiled.js` and save a
-source map to `script-compiled.js.map`.
-
-```sh
-$ 6to5 script.js --source-maps --out-file script-compiled.js
-```
-
-Compile the file `script.js` and output it to `script-compiled.js` with a source
-map embedded in a comment at the bottom.
-
-```sh
-$ 6to5 script.js --source-maps-inline --out-file script-compiled.js
-```
-
-Compile the entire `src` directory and output it to the `lib` directory.
-
-```sh
-$ 6to5 src --out-dir lib
-```
-
-Compile the entire `src` directory and output it to the one concatenated file.
-
-```sh
-$ 6to5 src --out-file script-compiled.js
-```
-
-Pipe a file in via stdin and output it to `script-compiled.js`
-
-```sh
-$ 6to5 --out-file script-compiled.js < script.js
-```
-
-### Node
-
-Launch a repl.
-
-```sh
-$ 6to5-node
-```
-
-Evaluate code.
-
-```sh
-$ 6to5-node -e "class Test { }"
-```
-
-Compile and run `test.js`.
-
-```sh
-$ 6to5-node test
-```
-
-## Node
-
-```javascript
-var to5 = require("6to5");
-```
-
-### to5.transform(code, [opts]);
-
-```javascript
-var result = to5.transform("code();", options);
-result.code;
-result.map;
-result.ast;
-```
-
-### to5.transformFileSync(filename, [opts])
-
-```javascript
-to5.transformFileSync("filename.js", options).code;
-```
-
-### to5.transformFile(filename, [opts], callback)
-
-```javascript
-to5.transformFile("filename.js", options, function (err, result) {
-  result.code;
-});
-```
-
-### to5.transform.fromAst(ast, [code], [opts])
-
-```javascript
-var result = to5.transform.fromAst(ast, "var a = 2;", opts);
-result.code;
-result.map;
-result.ast;
-```
-
-#### Options
-
-```javascript
-{
-  // Filename for use in errors etc.
-  // Default: "unknown"
-  filename: "filename",
-
-  // Filename relative to `sourceRoot`
-  // Default: `filename` option.
-  filenameRelative: "",
-
-  // List of transformers to EXCLUDE.
-  // Run `6to5 --help` to see a full list of transformers.
-  blacklist: [],
-
-  // List of transformers to ONLY use.
-  // Run `6to5 --help` to see a full list of transformers.
-  whitelist: [],
-
-  // Module formatter to use
-  // Run `6to5 --help` to see a full list of module formatters.
-  // Default: "common"
-  modules: "common",
-
-  // If truthy, adds a `map` property to returned output.
-  // If set to "inline", a comment with a sourceMappingURL directive is added to
-  // the bottom of the returned code.
-  // Default: false
-  sourceMap: true,
-
-  // Set `file` on returned source map.
-  // Default: `filenameRelative` option.
-  sourceMapName: "filename",
-
-  // Set `sources[0]` on returned source map.
-  // Default: `filenameRelative` option.
-  sourceFileName: "filename",
-
-  // The root from which all sources are relative
-  // Default: `moduleRoot` option.
-  sourceRoot: "assets/scripts",
-
-  // Optional prefix for the AMD module formatter that will be prepend to the
-  // filename on module definitions
-  // Default: `sourceRoot` option.
-  moduleRoot: "my-app",
-
-  // If truthy, insert an explicit id for each defined AMD/System module.
-  // By default, AMD/System modules are anonymous.
-  // Default: false
-  moduleIds: true,
-
-  // Optionally replace all 6to5 helper declarations with a referenece to this
-  // variable. If set to `true` then the default namespace is used "to5Runtime".
-  // Default: false
-  runtime: true,
-
-  // Enable support for experimental ES7 features
-  // Default: false
-  experimental: true,
-
-  // Set this to `false` if you don't want the transformed AST in the returned
-  // result
-  // Default: true
-  ast: true,
-
-  // Set this to `false` if you don't want the transformed code in the returned
-  // result
-  // Default: true
-  code: true,
-
-  format: {
-    // Output comments in generated output
-    // Default: true
-    comments: true,
-
-    // Do not include superfluous whitespace characters and line terminators
-    // Default: false
-    compact: false,
-
-    indent: {
-      // Preserve parentheses in new expressions that have no arguments
-      // Default: true
-      parentheses: true,
-
-      // Adjust the indentation of multiline comments to keep asterisks vertically aligned
-      // Default: true
-      adjustMultilineComment: true,
-
-      // Indent string
-      // Default: "  "
-      style: "  ",
-
-      // Base indent level
-      // Default: 0
-      base: 0
-    }
-  }
-}
-```
-
-### Require hook
-
-All subsequent files required by node with the extensions `.es6`, `.es` and `.js` will
-be transformed by 6to5. The polyfill specified in [Polyfill](polyfill.md) is
-also required; but this is automatically loaded when using:
-
-Source maps are automatically configured so if any errors a thrown then line
-number info is mapped and you'll get the correct source location.
-
-```javascript
-require("6to5/register");
-```
-
-**NOTE:** By default all requires to `node_modules` will be ignored. You can
-override this by passing an ignore regex via:
-
-```javascript
-require("6to5/register")({
-  // This will override `node_modules` ignoring - you can alternatively pass
-  // a regex
-  ignore: false
-});
-```
-
-**NOTE:** Using 6to5-node or `require("6to5/register")`, 6to5 will check what features are available in the current environment and blacklists them if they're supported.
-
-#### Options
-
-```javascript
-require("6to5/register")({
-  // Optional ignore regex - if any filenames **do** match this regex then they
-  // aren't compiled
-  ignore: /regex/,
-
-  // Optional only regex - if any filenames **don't** match this regex then they
-  // aren't compiled
-  only: /my_es6_folder/,
-
-  // See options above for usage
-  whitelist: [],
-  blacklist: [],
-
-  // This will remove the currently hooked extensions of .es6 and .js so you'll
-  // have to add them back if you want them to be used again.
-  extensions: [".js", ".es6"],
-
-  // Enables `roadrunner` cache that will save to a `.roadrunner.json` file in your cwd
-  // Do not check this into git as it's user-specific
-  cache: true
-});
-```

lib/6to5/browser.js

@@ -1,5 +1,9 @@
+"use strict";
+
 var transform = module.exports = require("./transformation/transform");
 
+transform.version = require("../../package").version;
+
 transform.transform = transform;
 
 transform.run = function (code, opts) {

lib/6to5/file.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = File;
 
 var SHEBANG_REGEX = /^\#\!.*/;
@@ -24,6 +26,7 @@ File.helpers = [
   "prototype-properties",
   "apply-constructor",
   "tagged-template-literal",
+  "tagged-template-literal-loose",
   "interop-require",
   "to-array",
   "sliced-to-array",
@@ -35,32 +38,38 @@ File.helpers = [
   "async-to-generator",
   "interop-require-wildcard",
   "typeof",
-  "exports-wildcard"
+  "extends",
+  "get"
 ];
 
 File.excludeHelpersFromRuntime = [
   "async-to-generator",
-  "typeof"
+  "typeof",
+  "tagged-template-literal-loose"
 ];
 
 File.normaliseOptions = function (opts) {
   opts = _.cloneDeep(opts || {});
 
   _.defaults(opts, {
-    experimental: false,
-    playground:   false,
-    whitespace:   true,
-    moduleIds:    opts.amdModuleIds || false,
-    blacklist:    [],
-    whitelist:    [],
-    sourceMap:    false,
-    optional:     [],
-    comments:     true,
-    filename:     "unknown",
-    modules:      "common",
-    runtime:      false,
-    code:         true,
-    ast:          true
+    keepModuleIdExtensions: false,
+    includeRegenerator:     false,
+    experimental:           false,
+    reactCompat:            false,
+    playground:             false,
+    whitespace:             true,
+    moduleIds:              opts.amdModuleIds || false,
+    blacklist:              [],
+    whitelist:              [],
+    sourceMap:              false,
+    optional:               [],
+    comments:               true,
+    filename:               "unknown",
+    modules:                "common",
+    runtime:                false,
+    loose:                  [],
+    code:                   true,
+    ast:                    true
   });
 
   // normalise windows path separators to unix
@@ -68,6 +77,23 @@ File.normaliseOptions = function (opts) {
 
   opts.blacklist = util.arrayify(opts.blacklist);
   opts.whitelist = util.arrayify(opts.whitelist);
+  opts.optional  = util.arrayify(opts.optional);
+  opts.loose     = util.arrayify(opts.loose);
+
+  if (_.contains(opts.loose, "all")) {
+    opts.loose = Object.keys(transform.transformers);
+  }
+
+  // todo: remove in 3.0.0
+  _.each({
+    fastForOf: "forOf",
+    classesFastSuper: "classes"
+  }, function (newTransformer, oldTransformer) {
+    if (_.contains(opts.optional, oldTransformer)) {
+      _.pull(opts.optional, oldTransformer);
+      opts.loose.push(newTransformer);
+    }
+  });
 
   _.defaults(opts, {
     moduleRoot: opts.sourceRoot
@@ -97,10 +123,15 @@ File.normaliseOptions = function (opts) {
   transform._ensureTransformerNames("blacklist", opts.blacklist);
   transform._ensureTransformerNames("whitelist", opts.whitelist);
   transform._ensureTransformerNames("optional", opts.optional);
+  transform._ensureTransformerNames("loose", opts.loose);
 
   return opts;
 };
 
+File.prototype.isLoose = function (key) {
+  return _.contains(this.opts.loose, key);
+};
+
 File.prototype.getTransformers = function () {
   var file = this;
   var transformers = [];
@@ -300,7 +331,10 @@ File.prototype.generateUid = function (name, scope) {
 };
 
 File.prototype.generateUidIdentifier = function (name, scope) {
-  return t.identifier(this.generateUid(name, scope));
+  scope = scope || this.scope;
+  var id = t.identifier(this.generateUid(name, scope));
+  scope.add(id);
+  return id;
 };
 
 File.prototype._generateUid = function (name) {

lib/6to5/generation/buffer.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = Buffer;
 
 var util = require("../util");
@@ -61,39 +63,63 @@ Buffer.prototype.space = function () {
 Buffer.prototype.removeLast = function (cha) {
   if (!this.isLast(cha)) return;
 
-  this.buf = this.buf.slice(0, -1);
+  this.buf = this.buf.substr(0, this.buf.length - 1);
   this.position.unshift(cha);
 };
 
 Buffer.prototype.newline = function (i, removeLast) {
   if (this.format.compact) return;
-
-  if (_.isBoolean(i)) {
-    removeLast = i;
-    i = null;
-  }
+  removeLast = removeLast || false;
 
   if (_.isNumber(i)) {
     if (this.endsWith("{\n")) i--;
     if (this.endsWith(util.repeat(i, "\n"))) return;
 
-    var self = this;
-    _.times(i, function () {
-      self.newline(null, removeLast);
-    });
+    while (i--) {
+      this._newline(removeLast);
+    }
     return;
   }
 
+  if (_.isBoolean(i)) {
+    removeLast = i;
+  }
+
+  this._newline(removeLast);
+};
+
+Buffer.prototype._newline = function (removeLast) {
   if (removeLast && this.isLast("\n")) this.removeLast("\n");
 
   this.removeLast(" ");
 
   // remove whitespace if last character was a newline
-  this.buf = this.buf.replace(/\n +$/, "\n");
-
+  this._removeSpacesAfterLastNewline();
   this._push("\n");
 };
 
+/**
+ * If buffer ends with a newline and some spaces after it, trim those spaces.
+ */
+Buffer.prototype._removeSpacesAfterLastNewline = function () {
+  var lastNewlineIndex = this.buf.lastIndexOf('\n');
+  if (lastNewlineIndex === -1)
+    return;
+
+  var index = this.buf.length - 1;
+  while (index > lastNewlineIndex) {
+    if (this.buf[index] !== ' ') {
+      break;
+    }
+
+    index--;
+  }
+
+  if (index === lastNewlineIndex) {
+    this.buf = this.buf.substring(0, index + 1);
+  }
+};
+
 Buffer.prototype.push = function (str, noIndent) {
   if (this._indent && !noIndent && str !== "\n") {
     // we have an indent level and we aren't pushing a newline
@@ -115,13 +141,18 @@ Buffer.prototype._push = function (str) {
 };
 
 Buffer.prototype.endsWith = function (str) {
-  return this.buf.slice(-str.length) === str;
+  var d = this.buf.length - str.length;
+  return d >= 0 && this.buf.lastIndexOf(str) === d;
 };
 
 Buffer.prototype.isLast = function (cha, trimRight) {
   var buf = this.buf;
   if (trimRight) buf = util.trimRight(buf);
+  var last = buf[buf.length - 1];
 
-  var chars = [].concat(cha);
-  return _.contains(chars, _.last(buf));
+  if (Array.isArray(cha)) {
+    return _.contains(cha, last);
+  } else {
+    return cha === last;
+  }
 };

lib/6to5/generation/generator.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = function (ast, opts, code) {
   var gen = new CodeGenerator(ast, opts, code);
   return gen.generate();
@@ -125,7 +127,7 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
 
     var lines = 0;
 
-    if (node.start != null) {
+    if (node.start != null && !node._ignoreUserWhitespace) {
       // user node
       if (leading) {
         lines = self.whitespace.getNewlinesBefore(node);

lib/6to5/generation/generators/base.js

@@ -1,3 +1,5 @@
+"use strict";
+
 exports.File = function (node, print) {
   print(node.program);
 };

lib/6to5/generation/generators/classes.js

@@ -1,3 +1,5 @@
+"use strict";
+
 exports.ClassExpression =
 exports.ClassDeclaration = function (node, print) {
   this.push("class");

lib/6to5/generation/generators/comprehensions.js

@@ -1,3 +1,5 @@
+"use strict";
+
 exports.ComprehensionBlock = function (node, print) {
   this.keyword("for");
   this.push("(");

lib/6to5/generation/generators/expressions.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var util = require("../../util");
 var t    = require("../../types");
 var _    = require("lodash");
@@ -57,8 +59,28 @@ exports.ThisExpression = function () {
 
 exports.CallExpression = function (node, print) {
   print(node.callee);
+
   this.push("(");
-  print.join(node.arguments, { separator: ", " });
+
+  var separator = ",";
+
+  if (node._prettyCall) {
+    separator += "\n";
+    this.newline();
+    this.indent();
+  } else {
+    separator += " ";
+  }
+
+  print.join(node.arguments, {
+    separator: separator
+  });
+
+  if (node._prettyCall) {
+    this.newline();
+    this.dedent();
+  }
+
   this.push(")");
 };
 

lib/6to5/generation/generators/flow.js

@@ -1,3 +1,35 @@
-exports.ClassProperty = function () {
-  throw new Error("not implemented");
+"use strict";
+
+exports.AnyTypeAnnotation =
+exports.ArrayTypeAnnotation =
+exports.BooleanTypeAnnotation =
+exports.ClassProperty =
+exports.DeclareClass =
+exports.DeclareFunction =
+exports.DeclareModule =
+exports.DeclareVariable =
+exports.FunctionTypeAnnotation =
+exports.FunctionTypeParam =
+exports.GenericTypeAnnotation =
+exports.InterfaceExtends =
+exports.InterfaceDeclaration =
+exports.IntersectionTypeAnnotation =
+exports.NullableTypeAnnotation =
+exports.NumberTypeAnnotation =
+exports.StringLiteralTypeAnnotation =
+exports.StringTypeAnnotation =
+exports.TupleTypeAnnotation =
+exports.TypeofTypeAnnotation =
+exports.TypeAlias =
+exports.TypeAnnotation =
+exports.TypeParameterDeclaration =
+exports.TypeParameterInstantiation =
+exports.ObjectTypeAnnotation =
+exports.ObjectTypeCallProperty =
+exports.ObjectTypeIndexer =
+exports.ObjectTypeProperty =
+exports.QualifiedTypeIdentifier =
+exports.UnionTypeAnnotation =
+exports.VoidTypeAnnotation = function () {
+  // todo: implement these once we have a `--keep-types` option
 };

lib/6to5/generation/generators/jsx.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var t = require("../../types");
 var _ = require("lodash");
 

lib/6to5/generation/generators/methods.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var t = require("../../types");
 
 exports._params = function (node, print) {

lib/6to5/generation/generators/modules.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var t = require("../../types");
 var _ = require("lodash");
 

lib/6to5/generation/generators/playground.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var _ = require("lodash");
 
 _.each(["BindMemberExpression", "BindFunctionExpression"], function (type) {

lib/6to5/generation/generators/statements.js

@@ -1,4 +1,7 @@
-var t = require("../../types");
+"use strict";
+
+var util = require("../../util");
+var t    = require("../../types");
 
 exports.WithStatement = function (node, print) {
   this.keyword("with");
@@ -106,7 +109,16 @@ exports.TryStatement = function (node, print) {
   this.keyword("try");
   print(node.block);
   this.space();
-  print(node.handler);
+
+  // Esprima bug puts the catch clause in a `handlers` array.
+  // see https://code.google.com/p/esprima/issues/detail?id=433
+  // We run into this from regenerator generated ast.
+  if (node.handlers) {
+    print(node.handlers[0]);
+  } else {
+    print(node.handler);
+  }
+
   if (node.finalizer) {
     this.space();
     this.push("finally ");
@@ -157,7 +169,25 @@ exports.DebuggerStatement = function () {
 exports.VariableDeclaration = function (node, print, parent) {
   this.push(node.kind + " ");
 
-  print.join(node.declarations, { separator: ", " });
+  var hasInits = false;
+  // don't add whitespace to loop heads
+  if (!t.isFor(parent)) {
+    for (var i = 0; i < node.declarations.length; i++) {
+      if (node.declarations[i].init) {
+        // has an init so let's split it up over multiple lines
+        hasInits = true;
+      }
+    }
+  }
+
+  var sep = ",";
+  if (hasInits) {
+    sep += "\n" + util.repeat(node.kind.length + 1);
+  } else {
+    sep += " ";
+  }
+
+  print.join(node.declarations, { separator: sep });
 
   if (!t.isFor(parent)) {
     this.semicolon();

lib/6to5/generation/generators/template-literals.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var _ = require("lodash");
 
 exports.TaggedTemplateExpression = function (node, print) {

lib/6to5/generation/generators/types.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var _ = require("lodash");
 
 exports.Identifier = function (node) {

lib/6to5/generation/node/index.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = Node;
 
 var whitespace = require("./whitespace");
@@ -6,14 +8,19 @@ var t          = require("../../types");
 var _          = require("lodash");
 
 var find = function (obj, node, parent) {
+  if (!obj) return;
   var result;
 
-  _.each(obj, function (fn, type) {
-    if (t["is" + type](node)) {
+  var types = Object.keys(obj);
+  for (var i = 0; i < types.length; i++) {
+    var type = types[i];
+
+    if (t.is(type, node)) {
+      var fn = obj[type];
       result = fn(node, parent);
-      if (result != null) return false;
+      if (result != null) break;
     }
-  });
+  }
 
   return result;
 };
@@ -23,13 +30,11 @@ function Node(node, parent) {
   this.node   = node;
 }
 
-Node.prototype.isUserWhitespacable = function () {
-  return t.isUserWhitespacable(this.node);
+Node.isUserWhitespacable = function (node) {
+  return t.isUserWhitespacable(node);
 };
 
-Node.prototype.needsWhitespace = function (type) {
-  var parent = this.parent;
-  var node   = this.node;
+Node.needsWhitespace = function (node, parent, type) {
   if (!node) return 0;
 
   if (t.isExpressionStatement(node)) {
@@ -46,18 +51,15 @@ Node.prototype.needsWhitespace = function (type) {
   return lines || 0;
 };
 
-Node.prototype.needsWhitespaceBefore = function () {
-  return this.needsWhitespace("before");
+Node.needsWhitespaceBefore = function (node, parent) {
+  return Node.needsWhitespace(node, parent, "before");
 };
 
-Node.prototype.needsWhitespaceAfter = function () {
-  return this.needsWhitespace("after");
+Node.needsWhitespaceAfter = function (node, parent) {
+  return Node.needsWhitespace(node, parent, "after");
 };
 
-Node.prototype.needsParens = function () {
-  var parent = this.parent;
-  var node   = this.node;
-
+Node.needsParens = function (node, parent) {
   if (!parent) return false;
 
   if (t.isNewExpression(parent) && parent.callee === node) {
@@ -72,10 +74,7 @@ Node.prototype.needsParens = function () {
   return find(parens, node, parent);
 };
 
-Node.prototype.needsParensNoLineTerminator = function () {
-  var parent = this.parent;
-  var node   = this.node;
-
+Node.needsParensNoLineTerminator = function (node, parent) {
   if (!parent) return false;
 
   // no comments
@@ -95,11 +94,18 @@ Node.prototype.needsParensNoLineTerminator = function () {
   return false;
 };
 
-_.each(Node.prototype, function (fn, key) {
-  Node[key] = function (node, parent) {
-    var n = new Node(node, parent);
+_.each(Node, function (fn, key) {
+  Node.prototype[key] = function () {
+    // Avoid leaking arguments to prevent deoptimization
+    var args = new Array(arguments.length + 2);
 
-    var args = _.toArray(arguments).slice(2);
-    return n[key].apply(n, args);
+    args[0] = this.node;
+    args[1] = this.parent;
+
+    for (var i = 0; i < args.length; i++) {
+      args[i + 2] = arguments[i];
+    }
+
+    return Node[key].apply(null, args);
   };
 });

lib/6to5/generation/node/parentheses.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var t = require("../../types");
 var _ = require("lodash");
 
@@ -21,6 +23,13 @@ _.each([
   });
 });
 
+exports.UpdateExpression = function (node, parent) {
+  if (t.isMemberExpression(parent) && parent.object === node) {
+    // (foo++).test()
+    return true;
+  }
+};
+
 exports.ObjectExpression = function (node, parent) {
   if (t.isExpressionStatement(parent)) {
     // ({ foo: "bar" });
@@ -142,8 +151,10 @@ exports.ConditionalExpression = function (node, parent) {
     return true;
   }
 
-  if (t.isCallExpression(parent) && parent.callee === node) {
-    return true;
+  if (t.isCallExpression(parent) || t.isNewExpression(parent)) {
+    if (parent.callee === node) {
+      return true;
+    }
   }
 
   if (t.isConditionalExpression(parent) && parent.test === node) {

lib/6to5/generation/node/whitespace.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var _ = require("lodash");
 var t = require("../../types");
 
@@ -62,11 +64,15 @@ _.each({
   CallExpression: { after: 1 },
   Literal: { after: 1 }
 }, function (amounts, type) {
-  if (_.isNumber(amounts)) amounts = { after: amounts, before: amounts };
+  if (_.isNumber(amounts)) {
+    amounts = { after: amounts, before: amounts };
+  }
 
-  _.each(amounts, function (amount, key) {
-    exports[key].nodes[type] = function () {
-      return amount;
-    };
+  _.each([type].concat(t.FLIPPED_ALIAS_KEYS[type] || []), function (type) {
+    _.each(amounts, function (amount, key) {
+      exports[key].nodes[type] = function () {
+        return amount;
+      };
+    });
   });
 });

lib/6to5/generation/position.js

@@ -1,6 +1,6 @@
-module.exports = Position;
+"use strict";
 
-var _ = require("lodash");
+module.exports = Position;
 
 function Position() {
   this.line = 1;
@@ -8,26 +8,22 @@ function Position() {
 }
 
 Position.prototype.push = function (str) {
-  var self = this;
-
-  _.each(str, function (cha) {
-    if (cha === "\n") {
-      self.line++;
-      self.column = 0;
+  for (var i = 0; i < str.length; i++) {
+    if (str[i] === "\n") {
+      this.line++;
+      this.column = 0;
     } else {
-      self.column++;
+      this.column++;
     }
-  });
+  }
 };
 
 Position.prototype.unshift = function (str) {
-  var self = this;
-
-  _.each(str, function (cha) {
-    if (cha === "\n") {
-      self.line--;
+  for (var i = 0; i < str.length; i++) {
+    if (str[i] === "\n") {
+      this.line--;
     } else {
-      self.column--;
+      this.column--;
     }
-  });
+  }
 };

lib/6to5/generation/source-map.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = SourceMap;
 
 var sourceMap = require("source-map");

lib/6to5/generation/whitespace.js

@@ -1,25 +1,62 @@
+"use strict";
+
 module.exports = Whitespace;
 
-var _ = require("lodash");
+var _    = require("lodash");
+
+/**
+ * Returns `i`th number from `base`, continuing from 0 when `max` is reached.
+ * Useful for shifting `for` loop by a fixed number but going over all items.
+ *
+ * @param {Number} i Current index in the loop
+ * @param {Number} base Start index for which to return 0
+ * @param {Number} max Array length
+ * @returns {Number} shiftedIndex
+ */
+function getLookupIndex(i, base, max) {
+  i += base;
+
+  if (i >= max)
+    i -= max;
+
+  return i;
+}
 
 function Whitespace(tokens, comments) {
   this.tokens = _.sortBy(tokens.concat(comments), "start");
-  this.used   = [];
+  this.used   = {};
+
+  // Profiling this code shows that while generator passes over it, indexes
+  // returned by `getNewlinesBefore` and `getNewlinesAfter` are always increasing.
+
+  // We use this implementation detail for an optimization: instead of always
+  // starting to look from `this.tokens[0]`, we will start `for` loops from the
+  // previous successful match. We will enumerate all tokens—but the common
+  // case will be much faster.
+
+  this._lastFoundIndex = 0;
 }
 
 Whitespace.prototype.getNewlinesBefore = function (node) {
   var startToken;
   var endToken;
   var tokens = this.tokens;
+  var token;
+
+  for (var j = 0; j < tokens.length; j++) {
+    // optimize for forward traversal by shifting for loop index
+    var i = getLookupIndex(j, this._lastFoundIndex, this.tokens.length);
+    token = tokens[i];
 
-  _.each(tokens, function (token, i) {
     // this is the token this node starts with
     if (node.start === token.start) {
       startToken = tokens[i - 1];
       endToken = token;
-      return false;
+
+      this._lastFoundIndex = i;
+      break;
     }
-  });
+  }
 
   return this.getNewlinesBetween(startToken, endToken);
 };
@@ -28,32 +65,44 @@ Whitespace.prototype.getNewlinesAfter = function (node) {
   var startToken;
   var endToken;
   var tokens = this.tokens;
+  var token;
+
+  for (var j = 0; j < tokens.length; j++) {
+    // optimize for forward traversal by shifting for loop index
+    var i = getLookupIndex(j, this._lastFoundIndex, this.tokens.length);
+    token = tokens[i];
 
-  _.each(tokens, function (token, i) {
     // this is the token this node ends with
     if (node.end === token.end) {
       startToken = token;
       endToken = tokens[i + 1];
-      return false;
+
+      this._lastFoundIndex = i;
+      break;
     }
-  });
+  }
 
   if (endToken.type.type === "eof") {
     return 1;
   } else {
-    return this.getNewlinesBetween(startToken, endToken);
+    var lines = this.getNewlinesBetween(startToken, endToken);
+    if (node.type === "Line" && !lines) {
+      // line comment
+      return 1;
+    } else {
+      return lines;
+    }
   }
 };
 
 Whitespace.prototype.getNewlinesBetween = function (startToken, endToken) {
   var start = startToken ? startToken.loc.end.line : 1;
   var end   = endToken.loc.start.line;
-
   var lines = 0;
 
   for (var line = start; line < end; line++) {
-    if (!_.contains(this.used, line)) {
-      this.used.push(line);
+    if (typeof this.used[line] === 'undefined') {
+      this.used[line] = true;
       lines++;
     }
   }

lib/6to5/index.js

@@ -1,8 +1,12 @@
+"use strict";
+
 var transform = require("./transformation/transform");
 var util      = require("./util");
 var fs        = require("fs");
 var _         = require("lodash");
 
+exports.version = require("../../package").version;
+
 exports.types = require("./types");
 
 exports.runtime = require("./runtime-generator");

lib/6to5/patch.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var t = require("./types");
 var _ = require("lodash");
 

lib/6to5/polyfill.js

@@ -1,2 +1,4 @@
+"use strict";
+
 require("core-js/shim");
 require("regenerator/runtime");

lib/6to5/register-browser.js

@@ -1,4 +1,7 @@
-// Required to safely use 6to5/register within a browserify codebase.
+"use strict";
+
+// required to safely use 6to5/register within a browserify codebase
+
 module.exports = function () {};
 
 require("./polyfill");

lib/6to5/register.js

@@ -1,3 +1,5 @@
+"use strict";
+
 require("./polyfill");
 
 var sourceMapSupport = require("source-map-support");
@@ -21,51 +23,6 @@ sourceMapSupport.install({
   }
 });
 
-//
-
-var blacklist  = [];
-
-var blacklistTest = function (transformer, code) {
-  try {
-    if (_.isFunction(code)) {
-      code();
-    } else {
-      new Function(code);
-    }
-    blacklist.push(transformer);
-  } catch (err) {
-    if (err.name !== "SyntaxError") throw err;
-  }
-};
-
-blacklistTest("arrayComprehension", "var foo = [for (foo of bar) foo * foo];");
-blacklistTest("generatorComprehension", "var foo = (for (foo of bar) foo * foo)");
-blacklistTest("arrowFunctions", "var foo = x => x * x;");
-blacklistTest("classes", "class Foo {}");
-blacklistTest("computedPropertyNames", "var foo = { [foo]: bar };");
-blacklistTest("constants", function () {
-  try {
-    new Function("const foo = 'foo';\nfoo = 'wow';");
-  } catch (err) {
-    return; // constants are supported
-  }
-  throw new SyntaxError;
-});
-blacklistTest("defaultParamaters", "var foo = function (bar = 0) {};");
-blacklistTest("destructuring", "var { x, y } = { x: 0, y: 0 };");
-blacklistTest("forOf", "for (var foo of bar) {}");
-blacklistTest("generators", "function* foo() {}\nasync function bar() {}"); // generators/async functions delegated to same transformer
-blacklistTest("letScoping", "let foo = 0;");
-blacklistTest("modules", 'import foo from "from";');
-blacklistTest("propertyMethodAssignment", "{ get foo() {} }");
-blacklistTest("propertyNameShorthand", "var foo = { x, y };");
-blacklistTest("restParameters", "function foo(...bar) {}");
-blacklistTest("spread", "foo(...bar);");
-blacklistTest("templateLiterals", "var foo = `foo`;");
-blacklistTest("unicodeRegex", function () { new RegExp("foo", "u"); });
-
-//
-
 var transformOpts = {};
 var ignoreRegex   = /node_modules/;
 var onlyRegex;
@@ -95,7 +52,6 @@ var loader = function (m, filename) {
 
   result = result || to5.transformFileSync(filename, _.extend({
     whitelist: whitelist,
-    blacklist: blacklist,
     sourceMap: true,
     ast:       false
   }, transformOpts));
@@ -123,7 +79,7 @@ var hookExtensions = function (_exts) {
   });
 };
 
-hookExtensions([".es6", ".es", ".js"]);
+hookExtensions(util.canCompile.EXTENSIONS);
 
 module.exports = function (opts) {
   // normalise options

lib/6to5/runtime-generator.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var generator = require("./generation/generator");
 var util      = require("./util");
 var File      = require("./file");
@@ -20,7 +22,7 @@ module.exports = function (namespace) {
 
   _.each(File.helpers, function (name) {
     if (_.contains(File.excludeHelpersFromRuntime, name)) {
-      return false;
+      return;
     }
 
     var key = t.identifier(t.toIdentifier(name));

lib/6to5/to-fast-properties.js

@@ -0,0 +1,17 @@
+"use strict";
+
+/**
+ * A trick from Bluebird to force V8 to use fast properties for an object.
+ * Read more: http://stackoverflow.com/questions/24987896/
+ *
+ * Use %HasFastProperties(obj) and --allow-natives-syntax to check whether
+ * a particular object already has fast properties.
+ */
+
+module.exports = function toFastProperties(obj) {
+  /*jshint -W027*/
+  function f() {}
+  f.prototype = obj;
+  return f;
+  eval(obj);
+};

lib/6to5/transformation/helpers/build-binary-assignment-operator-transformer.js

@@ -0,0 +1,45 @@
+"use strict";
+
+var explode = require("./explode-assignable-expression");
+var t       = require("../../types");
+
+module.exports = function (exports, opts) {
+  var isAssignment = function (node) {
+    return node.operator === opts.operator + "=";
+  };
+
+  var buildAssignment = function (left, right) {
+    return t.assignmentExpression("=", left, right);
+  };
+
+  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+    var expr = node.expression;
+    if (!isAssignment(expr)) return;
+
+    var nodes    = [];
+    var exploded = explode(expr.left, nodes, file, scope, true);
+
+    nodes.push(t.expressionStatement(
+      buildAssignment(exploded.ref, opts.build(exploded.uid, expr.right))
+    ));
+
+    return nodes;
+  };
+
+  exports.AssignmentExpression = function (node, parent, scope, context, file) {
+    if (t.isExpressionStatement(parent)) return;
+    if (!isAssignment(node)) return;
+
+    var nodes    = [];
+    var exploded = explode(node.left, nodes, file, scope);
+    nodes.push(opts.build(exploded.uid, node.right));
+    nodes.push(exploded.ref);
+
+    return t.toSequenceExpression(nodes, scope);
+  };
+
+  exports.BinaryExpression = function (node) {
+    if (node.operator !== opts.operator) return;
+    return opts.build(node.left, node.right);
+  };
+};

lib/6to5/transformation/helpers/build-comprehension.js

@@ -0,0 +1,25 @@
+"use strict";
+
+var t = require("../../types");
+
+module.exports = function build(node, buildBody) {
+  var self = node.blocks.shift();
+  if (!self) return;
+
+  var child = build(node, buildBody);
+  if (!child) {
+    // last item
+    child = buildBody();
+
+    // add a filter as this is our final stop
+    if (node.filter) {
+      child = t.ifStatement(node.filter, t.blockStatement([child]));
+    }
+  }
+
+  return t.forOfStatement(
+    t.variableDeclaration("let", [t.variableDeclarator(self.left)]),
+    self.right,
+    t.blockStatement([child])
+  );
+};

lib/6to5/transformation/helpers/build-conditional-assignment-operator-transformer.js

@@ -0,0 +1,45 @@
+"use strict";
+
+var explode = require("./explode-assignable-expression");
+var t       = require("../../types");
+
+module.exports = function (exports, opts) {
+  var buildAssignment = function (left, right) {
+    return t.assignmentExpression("=", left, right);
+  };
+
+  exports.ExpressionStatement = function (node, parent, scope, context, file) {
+    var expr = node.expression;
+    if (!opts.is(expr, file)) return;
+
+    var nodes = [];
+
+    var exploded = explode(expr.left, nodes, file, scope);
+
+    nodes.push(t.ifStatement(
+      opts.build(exploded.uid, file),
+      t.expressionStatement(buildAssignment(exploded.ref, expr.right))
+    ));
+
+    return nodes;
+  };
+
+  exports.AssignmentExpression = function (node, parent, scope, context, file) {
+    if (t.isExpressionStatement(parent)) return;
+    if (!opts.is(node, file)) return;
+
+    var nodes    = [];
+    var exploded = explode(node.left, nodes, file, scope);
+
+    nodes.push(t.logicalExpression(
+      "&&",
+      opts.build(exploded.uid, file),
+      buildAssignment(exploded.ref, node.right)
+    ));
+
+    // todo: duplicate expression node
+    nodes.push(exploded.ref);
+
+    return t.toSequenceExpression(nodes, scope);
+  };
+};

lib/6to5/transformation/helpers/explode-assignable-expression.js

@@ -0,0 +1,57 @@
+"use strict";
+
+var t = require("../../types");
+
+var getObjRef = function (node, nodes, file, scope) {
+  var ref;
+  if (t.isIdentifier(node)) {
+    ref = node;
+  } else if (t.isMemberExpression(node)) {
+    ref = node.object;
+  } else {
+    throw new Error("We can't explode this node type " + node.type);
+  }
+
+  var temp = scope.generateUidBasedOnNode(ref, file);
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(temp, ref)
+  ]));
+  return temp;
+};
+
+var getPropRef = function (node, nodes, file, scope) {
+  var prop = node.property;
+  var key = t.toComputedKey(node, prop);
+  if (t.isLiteral(key)) return key;
+
+  var temp = scope.generateUidBasedOnNode(prop, file);
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(temp, prop)
+  ]));
+  return temp;
+};
+
+module.exports = function (node, nodes, file, scope, allowedSingleIdent) {
+  var obj;
+  if (t.isIdentifier(node) && allowedSingleIdent) {
+    obj = node;
+  } else {
+    obj = getObjRef(node, nodes, file, scope);
+  }
+
+  var ref, uid;
+
+  if (t.isIdentifier(node)) {
+    ref = node;
+    uid = obj;
+  } else {
+    var prop = getPropRef(node, nodes, file, scope);
+    var computed = node.computed || t.isLiteral(prop);
+    uid = ref = t.memberExpression(obj, prop, computed);
+  }
+
+  return {
+    uid: uid,
+    ref: ref
+  };
+};

lib/6to5/transformation/helpers/name-method.js

@@ -0,0 +1,50 @@
+"use strict";
+
+var traverse = require("../../traverse");
+var util     = require("../../util");
+var t        = require("../../types");
+
+var traverser = {
+  enter: function (node, parent, scope, context, state) {
+    // check if this node is an identifier that matches the same as our function id
+    if (!t.isIdentifier(node, { name: state.id })) return;
+
+    // check if this node is the one referenced
+    if (!t.isReferenced(node, parent)) return;
+
+    // check that we don't have a local variable declared as that removes the need
+    // for the wrapper
+    var localDeclar = scope.get(state.id, true);
+    if (localDeclar !== state.outerDeclar) return;
+
+    state.selfReference = true;
+    context.stop();
+  }
+};
+
+exports.property = function (node, file, scope) {
+  var key = t.toComputedKey(node, node.key);
+  if (!t.isLiteral(key)) return node; // we can't set a function id with this
+
+  var id = t.toIdentifier(key.value);
+  key = t.identifier(id);
+
+  var state = {
+    id: id,
+    selfReference: false,
+    outerDeclar: scope.get(id, true),
+  };
+
+  traverse(node, traverser, scope, state);
+
+  if (state.selfReference) {
+    node.value = util.template("property-method-assignment-wrapper", {
+      FUNCTION: node.value,
+      FUNCTION_ID: key,
+      FUNCTION_KEY: file.generateUidIdentifier(id, scope),
+      WRAPPER_KEY: file.generateUidIdentifier(id + "Wrapper", scope)
+    });
+  } else {
+    node.value.id = key;
+  }
+};

lib/6to5/transformation/helpers/remap-async-to-generator.js

@@ -0,0 +1,31 @@
+"use strict";
+
+var traverse = require("../../traverse");
+var t        = require("../../types");
+
+module.exports = function (node, callId) {
+  node.async = false;
+  node.generator = true;
+
+  traverse(node, {
+    enter: function (node, parent, scope, context) {
+      if (t.isFunction(node)) context.skip();
+
+      if (t.isAwaitExpression(node)) {
+        node.type = "YieldExpression";
+      }
+    }
+  });
+
+  var call = t.callExpression(callId, [node]);
+
+  if (t.isFunctionDeclaration(node)) {
+    var declar = t.variableDeclaration("var", [
+      t.variableDeclarator(node.id, call)
+    ]);
+    declar._blockHoist = true;
+    return declar;
+  } else {
+    return call;
+  }
+};

lib/6to5/transformation/helpers/replace-supers.js

@@ -0,0 +1,246 @@
+"use strict";
+
+module.exports = ReplaceSupers;
+
+var traverse = require("../../traverse");
+var t        = require("../../types");
+
+/**
+ * Description
+ *
+ * @param {Object} methodNode
+ * @param {Object} className
+ * @param {Object} superName
+ * @param {Boolean} isLoose
+ * @param {File} file
+ */
+
+function ReplaceSupers(methodNode, className, superName, isLoose, file) {
+  this.topLevelThisReference = null;
+  this.methodNode            = methodNode;
+  this.className             = className;
+  this.superName             = superName;
+  this.isLoose               = isLoose;
+  this.file                  = file;
+}
+
+/**
+ * Gets a node representing the super class value of the named property.
+ *
+ * @example
+ *
+ *   _get(Object.getPrototypeOf(CLASS.prototype), "METHOD", this)
+ *
+ * @param {Node} property
+ * @param {boolean} isStatic
+ * @param {boolean} isComputed
+ *
+ * @returns {Node}
+ */
+
+ReplaceSupers.prototype.superProperty = function (property, isStatic, isComputed, thisExpression) {
+  return t.callExpression(
+    this.file.addHelper("get"),
+    [
+      t.callExpression(
+        t.memberExpression(t.identifier("Object"), t.identifier("getPrototypeOf")),
+        [
+          isStatic ? this.className : t.memberExpression(this.className, t.identifier("prototype"))
+        ]
+      ),
+      isComputed ? property : t.literal(property.name),
+      thisExpression
+    ]
+  );
+};
+
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {Object} id
+ * @param {Object} parent
+ * @returns {Object}
+ */
+
+ReplaceSupers.prototype.looseSuperProperty = function (methodNode, id, parent) {
+  var methodName = methodNode.key;
+  var superName  = this.superName || t.identifier("Function");
+
+  if (parent.property === id) {
+    return;
+  } else if (t.isCallExpression(parent, { callee: id })) {
+    // super(); -> ClassName.prototype.MethodName.call(this);
+    parent.arguments.unshift(t.thisExpression());
+
+    if (methodName.name === "constructor") {
+      // constructor() { super(); }
+      return t.memberExpression(superName, t.identifier("call"));
+    } else {
+      id = superName;
+
+      // foo() { super(); }
+      if (!methodNode.static) {
+        id = t.memberExpression(id, t.identifier("prototype"));
+      }
+
+      id = t.memberExpression(id, methodName, methodNode.computed);
+      return t.memberExpression(id, t.identifier("call"));
+    }
+  } else if (t.isMemberExpression(parent) && !methodNode.static) {
+    // super.test -> ClassName.prototype.test
+    return t.memberExpression(superName, t.identifier("prototype"));
+  } else {
+    return superName;
+  }
+};
+
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.replace = function () {
+  this.traverseLevel(this.methodNode.value, true);
+};
+
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @param {Boolean} topLevel
+ */
+
+ReplaceSupers.prototype.traverseLevel = function (node, topLevel) {
+  var self = this;
+
+  traverse(node, {
+    enter: function (node, parent, scope, context) {
+      if (t.isFunction(node) && !t.isArrowFunctionExpression(node)) {
+        // we need to call traverseLevel again so we're context aware
+        self.traverseLevel(node, false);
+        return context.skip();
+      }
+
+      if (t.isProperty(node, { method: true }) || t.isMethodDefinition(node)) {
+        // break on object methods
+        return context.skip();
+      }
+
+      var getThisReference = function () {
+        if (topLevel) {
+          // top level so `this` is the instance
+          return t.thisExpression();
+        } else {
+          // not in the top level so we need to create a reference
+          return self.getThisReference();
+        }
+      };
+
+      var callback = self.specHandle;
+      if (self.isLoose) callback = self.looseHandle;
+      return callback.call(self, getThisReference, node, parent);
+    }
+  });
+};
+
+/**
+ * Description
+ */
+
+ReplaceSupers.prototype.getThisReference = function () {
+  if (this.topLevelThisReference) {
+    return this.topLevelThisReference;
+  } else {
+    var ref = this.topLevelThisReference = this.file.generateUidIdentifier("this");
+    this.methodNode.value.body.body.unshift(t.variableDeclaration("var", [
+      t.variableDeclarator(this.topLevelThisReference, t.thisExpression())
+    ]));
+    return ref;
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Function} getThisReference
+ * @param {Object} node
+ * @param {Object} parent
+ */
+
+ReplaceSupers.prototype.looseHandle = function (getThisReference, node, parent) {
+  if (t.isIdentifier(node, { name: "super" })) {
+    return this.looseSuperProperty(this.methodNode, node, parent);
+  } else if (t.isCallExpression(node)) {
+    var callee = node.callee;
+    if (!t.isMemberExpression(callee)) return;
+    if (callee.object.name !== "super") return;
+
+    // super.test(); -> ClassName.prototype.MethodName.call(this);
+    t.appendToMemberExpression(callee, t.identifier("call"));
+    node.arguments.unshift(getThisReference());
+  }
+};
+
+/**
+ * Description
+ *
+ * @param {Function} getThisReference
+ * @param {Object} node
+ * @param {Object} parent
+ */
+
+ReplaceSupers.prototype.specHandle = function (getThisReference, node, parent) {
+  var methodNode = this.methodNode;
+  var property;
+  var computed;
+  var args;
+
+  if (t.isIdentifier(node, { name: "super" })) {
+    if (!(t.isMemberExpression(parent) && !parent.computed && parent.property === node)) {
+      throw this.file.errorWithNode(node, "illegal use of bare super");
+    }
+  } else if (t.isCallExpression(node)) {
+    var callee = node.callee;
+    if (t.isIdentifier(callee, { name: "super" })) {
+      // super(); -> _get(Object.getPrototypeOf(ClassName), "MethodName", this).call(this);
+      property = methodNode.key;
+      computed = methodNode.computed;
+      args = node.arguments;
+    } else {
+      if (!t.isMemberExpression(callee)) return;
+      if (callee.object.name !== "super") return;
+
+      // super.test(); -> _get(Object.getPrototypeOf(ClassName.prototype), "test", this).call(this);
+      property = callee.property;
+      computed = callee.computed;
+      args = node.arguments;
+    }
+  } else if (t.isMemberExpression(node)) {
+    if (!t.isIdentifier(node.object, { name: "super" })) return;
+
+    // super.name; -> _get(Object.getPrototypeOf(ClassName.prototype), "name", this);
+    property = node.property;
+    computed = node.computed;
+  }
+
+  if (!property) return;
+
+  var thisReference = getThisReference();
+  var superProperty = this.superProperty(property, methodNode.static, computed, thisReference);
+  if (args) {
+    if (args.length === 1 && t.isSpreadElement(args[0])) {
+      // super(...arguments);
+      return t.callExpression(
+        t.memberExpression(superProperty, t.identifier("apply")),
+        [thisReference, args[0].argument]
+      );
+    } else {
+      return t.callExpression(
+        t.memberExpression(superProperty, t.identifier("call")),
+        [thisReference].concat(args)
+      );
+    }
+  } else {
+    return superProperty;
+  }
+};

lib/6to5/transformation/helpers/use-strict.js

@@ -0,0 +1,21 @@
+"use strict";
+
+var t = require("../../types");
+
+exports.has = function (node) {
+  var first = node.body[0];
+  return t.isExpressionStatement(first) && t.isLiteral(first.expression, { value: "use strict" });
+};
+
+exports.wrap = function (node, callback) {
+  var useStrictNode;
+  if (exports.has(node)) {
+    useStrictNode = node.body.shift();
+  }
+
+  callback();
+
+  if (useStrictNode) {
+    node.body.unshift(useStrictNode);
+  }
+};

lib/6to5/transformation/modules/_default.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = DefaultFormatter;
 
 var traverse = require("../../traverse");
@@ -9,24 +11,77 @@ function DefaultFormatter(file) {
   this.file = file;
 
   this.localExports = this.getLocalExports();
+  this.localImports = this.getLocalImports();
+
   this.remapAssignments();
+
+  //this.checkCollisions();
 }
 
+var exportsTraverser = {
+  enter: function (node, parent, scope, context, localExports) {
+    var declar = node && node.declaration;
+    if (t.isExportDeclaration(node) && declar && t.isStatement(declar)) {
+      _.extend(localExports, t.getIds(declar, true));
+    }
+  }
+};
+
 DefaultFormatter.prototype.getLocalExports = function () {
   var localExports = {};
-
-  traverse(this.file.ast, {
-    enter: function (node) {
-      var declar = node && node.declaration;
-      if (t.isExportDeclaration(node) && declar && t.isStatement(declar)) {
-        _.extend(localExports, t.getIds(declar, true));
-      }
-    }
-  });
-
+  traverse(this.file.ast, exportsTraverser, null, localExports);
   return localExports;
 };
 
+var importsTraverser = {
+  enter: function (node, parent, scope, context, localImports) {
+    if (t.isImportDeclaration(node)) {
+      _.extend(localImports, t.getIds(node, true));
+    }
+  }
+};
+
+DefaultFormatter.prototype.getLocalImports = function () {
+  var localImports = {};
+  traverse(this.file.ast, importsTraverser, null, localImports);
+  return localImports;
+};
+
+var collissionsTraverser = {
+  enter: function (node, parent, scope, context, check) {
+    if (t.isAssignmentExpression(node)) {
+
+      var left = node.left;
+      if (t.isMemberExpression(left)) {
+        while (left.object) left = left.object;
+      }
+
+      check(left);
+    } else if (t.isDeclaration(node)) {
+      _.each(t.getIds(node, true), check);
+    }
+  }
+};
+
+DefaultFormatter.prototype.checkCollisions = function () {
+  // todo: all check export collissions
+
+  var localImports = this.localImports;
+  var file = this.file;
+
+  var isLocalReference = function (node) {
+    return t.isIdentifier(node) && _.has(localImports, node.name) && localImports[node.name] !== node;
+  };
+
+  var check = function (node) {
+    if (isLocalReference(node)) {
+      throw file.errorWithNode(node, "Illegal assignment of module import");
+    }
+  };
+
+  traverse(file.ast, collissionsTraverser, null, check);
+};
+
 DefaultFormatter.prototype.remapExportAssignment = function (node) {
   return t.assignmentExpression(
     "=",
@@ -49,9 +104,9 @@ DefaultFormatter.prototype.remapAssignments = function () {
   };
 
   traverse(this.file.ast, {
-    enter: function (node, parent, scope) {
+    enter: function (node, parent, scope, context, isLocalReference) {
       if (t.isUpdateExpression(node) && isLocalReference(node.argument, scope)) {
-        this.skip();
+        context.skip();
 
         // expand to long file assignment expression
         var assign = t.assignmentExpression(node.operator[0] + "=", node.argument, t.literal(1));
@@ -79,11 +134,11 @@ DefaultFormatter.prototype.remapAssignments = function () {
       }
 
       if (t.isAssignmentExpression(node) && isLocalReference(node.left, scope)) {
-        this.skip();
+        context.skip();
         return self.remapExportAssignment(node);
       }
     }
-  });
+  }, null, isLocalReference);
 };
 
 DefaultFormatter.prototype.getModuleName = function () {
@@ -105,11 +160,16 @@ DefaultFormatter.prototype.getModuleName = function () {
     filenameRelative = filenameRelative.replace(sourceRootRegEx, "");
   }
 
-  // remove extension
-  filenameRelative = filenameRelative.replace(/\.(.*?)$/, "");
+  if (!opts.keepModuleIdExtensions) {
+    // remove extension
+    filenameRelative = filenameRelative.replace(/\.(.*?)$/, "");
+  }
 
   moduleName += filenameRelative;
 
+  // normalise path separators
+  moduleName = moduleName.replace(/\\/g, "/");
+
   return moduleName;
 };
 
@@ -142,10 +202,11 @@ DefaultFormatter.prototype._exportSpecifier = function (getRef, specifier, node,
       nodes.push(this._exportsWildcard(getRef(), node));
     } else {
       var ref;
-      if (t.isSpecifierDefault(specifier.id) || this.noInteropRequire) {
-        ref = t.memberExpression(getRef(), specifier.id);
-      } else {
+      if (t.isSpecifierDefault(specifier) && !this.noInteropRequire) {
+        // importing a default so we need to normalise it
         ref = t.callExpression(this.file.addHelper("interop-require"), [getRef()]);
+      } else {
+        ref = t.memberExpression(getRef(), specifier.id);
       }
 
       // export { foo } from "test";
@@ -162,7 +223,8 @@ DefaultFormatter.prototype._exportSpecifier = function (getRef, specifier, node,
 };
 
 DefaultFormatter.prototype._exportsWildcard = function (objectIdentifier) {
-  return t.expressionStatement(t.callExpression(this.file.addHelper("exports-wildcard"), [
+  return t.expressionStatement(t.callExpression(this.file.addHelper("defaults"), [
+    t.identifier("exports"),
     t.callExpression(this.file.addHelper("interop-require-wildcard"), [objectIdentifier])
   ]));
 };
@@ -186,13 +248,13 @@ DefaultFormatter.prototype.exportDeclaration = function (node, nodes) {
   var assign;
 
   if (t.isVariableDeclaration(declar)) {
-    for (var i in declar.declarations) {
+    for (var i = 0; i < declar.declarations.length; i++) {
       var decl = declar.declarations[i];
 
       decl.init = this._exportsAssign(decl.id, decl.init, node).expression;
 
       var newDeclar = t.variableDeclaration(declar.kind, [decl]);
-      if (i === "0") t.inherits(newDeclar, declar);
+      if (i === 0) t.inherits(newDeclar, declar);
       nodes.push(newDeclar);
     }
   } else {

lib/6to5/transformation/modules/_strict.js

@@ -0,0 +1,14 @@
+"use strict";
+
+var util = require("../../util");
+
+module.exports = function (Parent) {
+  var Constructor = function () {
+    this.noInteropExport = true;
+    Parent.apply(this, arguments);
+  };
+
+  util.inherits(Constructor, Parent);
+
+  return Constructor;
+};

lib/6to5/transformation/modules/amd-strict.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./amd"));

lib/6to5/transformation/modules/amd.js

@@ -1,13 +1,16 @@
+"use strict";
+
 module.exports = AMDFormatter;
 
 var DefaultFormatter = require("./_default");
+var CommonFormatter  = require("./common");
 var util             = require("../../util");
 var t                = require("../../types");
 var _                = require("lodash");
 
 function AMDFormatter() {
-  DefaultFormatter.apply(this, arguments);
-  this.ids  = {};
+  CommonFormatter.apply(this, arguments);
+  this.ids = {};
 }
 
 util.inherits(AMDFormatter, DefaultFormatter);
@@ -30,12 +33,15 @@ AMDFormatter.prototype.transform = function (ast) {
 
   // build an array of module names
 
-  var names = [t.literal("exports")].concat(this.buildDependencyLiterals());
+  var names = [t.literal("exports")];
+  if (this.passModuleArg) names.push(t.literal("module"));
+  names = names.concat(this.buildDependencyLiterals());
   names = t.arrayExpression(names);
 
   // build up define container
 
   var params = _.values(this.ids);
+  if (this.passModuleArg) params.unshift(t.identifier("module"));
   params.unshift(t.identifier("exports"));
 
   var container = t.functionExpression(null, params, t.blockStatement(body));
@@ -96,6 +102,14 @@ AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
   ]));
 };
 
+AMDFormatter.prototype.exportDeclaration = function (node) {
+  if (node.default && !this.noInteropExport) {
+    this.passModuleArg = true;
+  }
+
+  CommonFormatter.prototype.exportDeclaration.apply(this, arguments);
+};
+
 AMDFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
   var self = this;
   return this._exportSpecifier(function () {

lib/6to5/transformation/modules/common-strict.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./common"));

lib/6to5/transformation/modules/common.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = CommonJSFormatter;
 
 var DefaultFormatter = require("./_default");
@@ -61,7 +63,7 @@ CommonJSFormatter.prototype.importDeclaration = function (node, nodes) {
 };
 
 CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
-  if (node.default) {
+  if (node.default && !this.noInteropRequire && !this.noInteropExport) {
     var declar = node.declaration;
     var assign;
 
@@ -83,10 +85,12 @@ CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
       // this export isn't a function so we can't hoist it to the top so we need to set it
       // at the very end of the file with something like:
       //
-      //   module.exports = Object.assign(exports["default"], exports)
+      //   module.exports = _extends(exports["default"], exports)
       //
 
-      assign = util.template("common-export-default-assign", true);
+      assign = util.template("common-export-default-assign", {
+        EXTENDS_HELPER: this.file.addHelper("extends")
+      }, true);
       assign._blockHoist = 0;
 
       nodes.push(assign);

lib/6to5/transformation/modules/ignore.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = IgnoreFormatter;
 
 var t = require("../../types");

lib/6to5/transformation/modules/system.js

@@ -1,7 +1,9 @@
+"use strict";
+
 module.exports = SystemFormatter;
 
 var AMDFormatter = require("./amd");
-var useStrict    = require("../transformers/use-strict");
+var useStrict    = require("../helpers/use-strict");
 var traverse     = require("../../traverse");
 var util         = require("../../util");
 var t            = require("../../types");
@@ -63,28 +65,31 @@ SystemFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
 
 SystemFormatter.prototype.buildRunnerSetters = function (block, hoistDeclarators) {
   return t.arrayExpression(_.map(this.ids, function (uid, source) {
-    var nodes = [];
+    var state = {
+      nodes: [],
+      hoistDeclarators: hoistDeclarators
+    };
 
     traverse(block, {
-      enter: function (node) {
+      enter: function (node, parent, scope, context, state) {
         if (node._importSource === source) {
           if (t.isVariableDeclaration(node)) {
             _.each(node.declarations, function (declar) {
-              hoistDeclarators.push(t.variableDeclarator(declar.id));
-              nodes.push(t.expressionStatement(
+              state.hoistDeclarators.push(t.variableDeclarator(declar.id));
+              state.nodes.push(t.expressionStatement(
                 t.assignmentExpression("=", declar.id, declar.init)
               ));
             });
           } else {
-            nodes.push(node);
+            state.nodes.push(node);
           }
 
-          this.remove();
+          context.remove();
         }
       }
-    });
+    }, null, state);
 
-    return t.functionExpression(null, [uid], t.blockStatement(nodes));
+    return t.functionExpression(null, [uid], t.blockStatement(state.nodes));
   }));
 };
 
@@ -112,10 +117,10 @@ SystemFormatter.prototype.transform = function (ast) {
 
   // hoist up all variable declarations
   traverse(block, {
-    enter: function (node, parent, scope) {
+    enter: function (node, parent, scope, context, hoistDeclarators) {
       if (t.isFunction(node)) {
         // nothing inside is accessible
-        return this.skip();
+        return context.skip();
       }
 
       if (t.isVariableDeclaration(node)) {
@@ -150,7 +155,8 @@ SystemFormatter.prototype.transform = function (ast) {
         return nodes;
       }
     }
-  });
+  }, null, hoistDeclarators);
+
   if (hoistDeclarators.length) {
     var hoistDeclar = t.variableDeclaration("var", hoistDeclarators);
     hoistDeclar._blockHoist = true;
@@ -159,19 +165,19 @@ SystemFormatter.prototype.transform = function (ast) {
 
   // hoist up function declarations for circular references
   traverse(block, {
-    enter: function (node) {
-      if (t.isFunction(node)) this.skip();
+    enter: function (node, parent, scope, context, handlerBody) {
+      if (t.isFunction(node)) context.skip();
 
       if (t.isFunctionDeclaration(node) || node._blockHoist) {
         handlerBody.push(node);
-        this.remove();
+        context.remove();
       }
     }
-  });
+  }, null, handlerBody);
 
   handlerBody.push(returnStatement);
 
-  if (useStrict._has(block)) {
+  if (useStrict.has(block)) {
     handlerBody.unshift(block.body.shift());
   }
 

lib/6to5/transformation/modules/umd-strict.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./umd"));

lib/6to5/transformation/modules/umd.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = UMDFormatter;
 
 var AMDFormatter = require("./amd");
@@ -25,22 +27,44 @@ UMDFormatter.prototype.transform = function (ast) {
   // factory
 
   var ids  = _.values(this.ids);
-  var args = [t.identifier("exports")].concat(ids);
+  var args = [t.identifier("exports")];
+  if (this.passModuleArg) args.push(t.identifier("module"));
+  args = args.concat(ids);
 
   var factory = t.functionExpression(null, args, t.blockStatement(body));
 
-  // runner
+  // amd
+
+  var defineArgs = [t.literal("exports")];
+  if (this.passModuleArg) defineArgs.push(t.literal("module"));
+  defineArgs = defineArgs.concat(names);
+  defineArgs = [t.arrayExpression(defineArgs)];
+
+  // common
+
+  var testExports = util.template("test-exports");
+  var testModule  = util.template("test-module");
+  var commonTests = this.passModuleArg ? t.logicalExpression("&&", testExports, testModule) : testExports;
+
+  var commonArgs = [t.identifier("exports")];
+  if (this.passModuleArg) commonArgs.push(t.identifier("module"));
+  commonArgs = commonArgs.concat(names.map(function (name) {
+    return t.callExpression(t.identifier("require"), [name]);
+  }));
+
+  // globals
+
+  //var umdArgs = [];
+
+  //
 
-  var defineArgs = [t.arrayExpression([t.literal("exports")].concat(names))];
   var moduleName = this.getModuleName();
   if (moduleName) defineArgs.unshift(t.literal(moduleName));
 
   var runner = util.template("umd-runner-body", {
     AMD_ARGUMENTS: defineArgs,
-
-    COMMON_ARGUMENTS: names.map(function (name) {
-      return t.callExpression(t.identifier("require"), [name]);
-    })
+    COMMON_TEST: commonTests,
+    COMMON_ARGUMENTS: commonArgs
   });
 
   //

lib/6to5/transformation/templates/array-comprehension-for-each.js

@@ -1,3 +0,0 @@
-ARRAY.forEach(function (KEY) {
-
-});

lib/6to5/transformation/templates/class-super-constructor-call-loose.js

@@ -0,0 +1,3 @@
+if (SUPER_NAME != null) {
+  SUPER_NAME.apply(this, arguments);
+}

lib/6to5/transformation/templates/class-super-constructor-call.js

@@ -1,3 +1,3 @@
-if (SUPER_NAME !== null) {
-  SUPER_NAME.apply(this, arguments);
+if (Object.getPrototypeOf(CLASS_NAME) !== null) {
+  Object.getPrototypeOf(CLASS_NAME).apply(this, arguments);
 }

lib/6to5/transformation/templates/common-export-default-assign.js

@@ -1 +1 @@
-module.exports = Object.assign(exports["default"], exports);
+module.exports = EXTENDS_HELPER(exports["default"], exports);

lib/6to5/transformation/templates/exports-wildcard.js

@@ -1,7 +0,0 @@
-(function (obj) {
-  for (var i in obj) {
-    if (exports[i] !== undefined) {
-      exports[i] = obj[i];
-    }
-  }
-})

lib/6to5/transformation/templates/extends.js

@@ -0,0 +1,9 @@
+(function (target) {
+  for (var i = 1; i < arguments.length; i++) {
+    var source = arguments[i];
+    for (var key in source) {
+      target[key] = source[key];
+    }
+  }
+  return target;
+})

lib/6to5/transformation/templates/for-of-loose.js

@@ -0,0 +1,13 @@
+for (var LOOP_OBJECT = OBJECT,
+         IS_ARRAY = Array.isArray(LOOP_OBJECT),
+         INDEX = 0,
+         LOOP_OBJECT = IS_ARRAY ? LOOP_OBJECT : LOOP_OBJECT[Symbol.iterator]();;) {
+  if (IS_ARRAY) {
+    if (INDEX >= LOOP_OBJECT.length) break;
+    ID = LOOP_OBJECT[INDEX++];
+  } else {
+    INDEX = LOOP_OBJECT.next();
+    if (INDEX.done) break;
+    ID = INDEX.value;
+  }
+}

lib/6to5/transformation/templates/get.js

@@ -0,0 +1,23 @@
+(function get(object, property, receiver) {
+  var desc = Object.getOwnPropertyDescriptor(object, property);
+
+  if (desc === undefined) {
+    var parent = Object.getPrototypeOf(object);
+
+    if (parent === null) {
+      return undefined;
+    } else {
+      return get(parent, property, receiver);
+    }
+  } else if ("value" in desc && desc.writable) {
+    return desc.value;
+  } else {
+    var getter = desc.get;
+
+    if (getter === undefined) {
+      return undefined;
+    }
+
+    return getter.call(receiver);
+  }
+});

lib/6to5/transformation/templates/inherits.js

@@ -1,14 +1,14 @@
-(function (child, parent) {
-  if (typeof parent !== "function" && parent !== null) {
-    throw new TypeError("Super expression must either be null or a function, not " + typeof parent);
+(function (subClass, superClass) {
+  if (typeof superClass !== "function" && superClass !== null) {
+    throw new TypeError("Super expression must either be null or a function, not " + typeof superClass);
   }
-  child.prototype = Object.create(parent && parent.prototype, {
+  subClass.prototype = Object.create(superClass && superClass.prototype, {
     constructor: {
-      value: child,
+      value: subClass,
       enumerable: false,
       writable: true,
       configurable: true
     }
   });
-  if (parent) child.__proto__ = parent;
+  if (superClass) subClass.__proto__ = superClass;
 })

lib/6to5/transformation/templates/object-define-properties-closure.js

@@ -1,5 +0,0 @@
-
-(function (KEY) {
-  CONTENT;
-  return KEY;
-})(OBJECT);

lib/6to5/transformation/templates/object-define-properties.js

@@ -1 +0,0 @@
-Object.defineProperties(OBJECT, PROPS);

lib/6to5/transformation/templates/rest.js

@@ -1,3 +1,3 @@
-for (var KEY = START; KEY < ARGUMENTS.length; KEY++) {
-  ARRAY[$__0] = ARGUMENTS[KEY];
+for (var LEN = ARGUMENTS.length, ARRAY = Array(ARRAY_LEN), KEY = START; KEY < LEN; KEY++) {
+  ARRAY[ARRAY_KEY] = ARGUMENTS[KEY];
 }

lib/6to5/transformation/templates/tagged-template-literal-loose.js

@@ -0,0 +1,4 @@
+(function (strings, raw) {
+  strings.raw = raw;
+  return strings;
+});

lib/6to5/transformation/templates/test-exports.js

@@ -0,0 +1 @@
+typeof exports !== "undefined"

lib/6to5/transformation/templates/test-module.js

@@ -0,0 +1 @@
+typeof module !== "undefined"

lib/6to5/transformation/templates/umd-runner-body.js

@@ -1,7 +1,7 @@
 (function (factory) {
   if (typeof define === "function" && define.amd) {
     define(AMD_ARGUMENTS, factory);
-  } else if (typeof exports !== "undefined") {
-    factory(exports, COMMON_ARGUMENTS);
+  } else if (COMMON_TEST) {
+    factory(COMMON_ARGUMENTS);
   }
 });

lib/6to5/transformation/transform.js

@@ -1,3 +1,5 @@
+"use strict";
+
 module.exports = transform;
 
 var Transformer = require("./transformer");
@@ -20,7 +22,7 @@ transform.fromAst = function (ast, code, opts) {
 };
 
 transform._ensureTransformerNames = function (type, keys) {
-  for (var i in keys) {
+  for (var i = 0; i < keys.length; i++) {
     var key = keys[i];
     if (!_.has(transform.transformers, key)) {
       throw new ReferenceError("unknown transformer " + key + " specified in " + type);
@@ -31,19 +33,23 @@ transform._ensureTransformerNames = function (type, keys) {
 transform.transformers = {};
 
 transform.moduleFormatters = {
-  common: require("./modules/common"),
-  system: require("./modules/system"),
-  ignore: require("./modules/ignore"),
-  amd:    require("./modules/amd"),
-  umd:    require("./modules/umd")
+  commonStrict: require("./modules/common-strict"),
+  umdStrict:    require("./modules/umd-strict"),
+  amdStrict:    require("./modules/amd-strict"),
+  common:       require("./modules/common"),
+  system:       require("./modules/system"),
+  ignore:       require("./modules/ignore"),
+  amd:          require("./modules/amd"),
+  umd:          require("./modules/umd")
 };
 
 _.each({
-  // spec
-  specBlockHoistFunctions:   require("./transformers/spec-block-hoist-functions"),
   specNoForInOfAssignment:   require("./transformers/spec-no-for-in-of-assignment"),
+  specSetters:               require("./transformers/spec-setters"),
+  specBlockScopedFunctions:  require("./transformers/spec-block-scoped-functions"),
 
   // playground
+  malletOperator:            require("./transformers/playground-mallet-operator"),
   methodBinding:             require("./transformers/playground-method-binding"),
   memoizationOperator:       require("./transformers/playground-memoization-operator"),
   objectGetterMemoization:   require("./transformers/playground-object-getter-memoization"),
@@ -59,26 +65,26 @@ _.each({
   arrowFunctions:            require("./transformers/es6-arrow-functions"),
   classes:                   require("./transformers/es6-classes"),
 
-  computedPropertyNames:     require("./transformers/es6-computed-property-names"),
-
   objectSpread:              require("./transformers/es7-object-spread"),
   exponentiationOperator:    require("./transformers/es7-exponentiation-operator"),
   spread:                    require("./transformers/es6-spread"),
   templateLiterals:          require("./transformers/es6-template-literals"),
   propertyMethodAssignment:  require("./transformers/es6-property-method-assignment"),
-  destructuring:             require("./transformers/es6-destructuring"),
+  computedPropertyNames:     require("./transformers/es6-computed-property-names"),
   defaultParameters:         require("./transformers/es6-default-parameters"),
+  restParameters:            require("./transformers/es6-rest-parameters"),
+  destructuring:             require("./transformers/es6-destructuring"),
   forOf:                     require("./transformers/es6-for-of"),
   unicodeRegex:              require("./transformers/es6-unicode-regex"),
   abstractReferences:        require("./transformers/es7-abstract-references"),
 
   constants:                 require("./transformers/es6-constants"),
   letScoping:                require("./transformers/es6-let-scoping"),
+  blockScopingTDZ:           require("./transformers/optional-block-scoping-tdz"),
 
   _blockHoist:               require("./transformers/_block-hoist"),
 
   generators:                require("./transformers/es6-generators"),
-  restParameters:            require("./transformers/es6-rest-parameters"),
 
   protoToAssign:             require("./transformers/optional-proto-to-assign"),
 
@@ -92,6 +98,7 @@ _.each({
   typeofSymbol:              require("./transformers/optional-typeof-symbol"),
   coreAliasing:              require("./transformers/optional-core-aliasing"),
   undefinedToVoid:           require("./transformers/optional-undefined-to-void"),
+  undeclaredVariableCheck:   require("./transformers/optional-undeclared-variable-check"),
 
   // spec
   specPropertyLiterals:         require("./transformers/spec-property-literals"),

lib/6to5/transformation/transformer.js

@@ -1,9 +1,30 @@
+"use strict";
+
 module.exports = Transformer;
 
 var traverse = require("../traverse");
 var t        = require("../types");
 var _        = require("lodash");
 
+function noop() { }
+
+function enter(node, parent, scope, context, args) {
+  var fns = args[1][node.type];
+  if (!fns) return;
+  return fns.enter(node, parent, scope, context, args[0]);
+}
+
+function exit(node, parent, scope, context, args) {
+  var fns = args[1][node.type];
+  if (!fns) return;
+  return fns.exit(node, parent, scope, context, args[0]);
+}
+
+var traverseOpts = {
+  enter: enter,
+  exit: exit
+};
+
 function Transformer(key, transformer, opts) {
   this.manipulateOptions = transformer.manipulateOptions;
   this.experimental      = !!transformer.experimental;
@@ -32,6 +53,9 @@ Transformer.prototype.normalise = function (transformer) {
 
     if (!_.isObject(fns)) return;
 
+    if (!fns.enter) fns.enter = noop;
+    if (!fns.exit) fns.exit = noop;
+
     transformer[type] = fns;
 
     var aliases = t.FLIPPED_ALIAS_KEYS[type];
@@ -54,28 +78,8 @@ Transformer.prototype.astRun = function (file, key) {
 };
 
 Transformer.prototype.transform = function (file) {
-  var transformer = this.transformer;
-
-  var build = function (exit) {
-    return function (node, parent, scope) {
-      var fns = transformer[node.type];
-      if (!fns) return;
-
-      var fn = fns.enter;
-      if (exit) fn = fns.exit;
-      if (!fn) return;
-
-      return fn(node, parent, file, scope);
-    };
-  };
-
   this.astRun(file, "before");
-
-  traverse(file.ast, {
-    enter: build(),
-    exit:  build(true)
-  });
-
+  traverse(file.ast, traverseOpts, null, [file, this.transformer]);
   this.astRun(file, "after");
 };
 

lib/6to5/transformation/transformers/_alias-functions.js

@@ -1,57 +1,64 @@
+"use strict";
+
 var traverse = require("../../traverse");
 var t        = require("../../types");
 
+var functionChildrenTraverser = {
+  enter: function (node, parent, scope, context, state) {
+    if (t.isFunction(node) && !node._aliasFunction) {
+      return context.skip();
+    }
+
+    if (node._ignoreAliasFunctions) return context.skip();
+
+    var getId;
+
+    if (t.isIdentifier(node) && node.name === "arguments") {
+      getId = state.getArgumentsId;
+    } else if (t.isThisExpression(node)) {
+      getId = state.getThisId;
+    } else {
+      return;
+    }
+
+    if (t.isReferenced(node, parent)) return getId();
+  }
+};
+
+var functionTraverser = {
+  enter: function (node, parent, scope, context, state) {
+    if (!node._aliasFunction) {
+      if (t.isFunction(node)) {
+        // stop traversal of this node as it'll be hit again by this transformer
+        return context.skip();
+      } else {
+        return;
+      }
+    }
+
+    // traverse all child nodes of this function and find `arguments` and `this`
+    traverse(node, functionChildrenTraverser, null, state);
+
+    return context.skip();
+  }
+};
+
 var go = function (getBody, node, file, scope) {
   var argumentsId;
   var thisId;
 
-  var getArgumentsId = function () {
-    return argumentsId = argumentsId || file.generateUidIdentifier("arguments", scope);
-  };
-
-  var getThisId = function () {
-    return thisId = thisId || file.generateUidIdentifier("this", scope);
+  var state = {
+    getArgumentsId: function () {
+      return argumentsId = argumentsId || file.generateUidIdentifier("arguments", scope);
+    },
+    getThisId: function () {
+      return thisId = thisId || file.generateUidIdentifier("this", scope);
+    }
   };
 
   // traverse the function and find all alias functions so we can alias
   // `arguments` and `this` if necessary
-  traverse(node, {
-    enter: function (node) {
-      if (!node._aliasFunction) {
-        if (t.isFunction(node)) {
-          // stop traversal of this node as it'll be hit again by this transformer
-          return this.skip();
-        } else {
-          return;
-        }
-      }
-
-      // traverse all child nodes of this function and find `arguments` and `this`
-      traverse(node, {
-        enter: function (node, parent) {
-          if (t.isFunction(node) && !node._aliasFunction) {
-            return this.skip();
-          }
-
-          if (node._ignoreAliasFunctions) return this.skip();
-
-          var getId;
-
-          if (t.isIdentifier(node) && node.name === "arguments") {
-            getId = getArgumentsId;
-          } else if (t.isThisExpression(node)) {
-            getId = getThisId;
-          } else {
-            return;
-          }
-
-          if (t.isReferenced(node, parent)) return getId();
-        }
-      });
-
-      return this.skip();
-    }
-  });
+  traverse(node, functionTraverser, null, state);
 
   var body;
 
@@ -71,14 +78,14 @@ var go = function (getBody, node, file, scope) {
   }
 };
 
-exports.Program = function (node, parent, file, scope) {
+exports.Program = function (node, parent, scope, context, file) {
   go(function () {
     return node.body;
   }, node, file, scope);
 };
 
 exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, file, scope) {
+exports.FunctionExpression = function (node, parent, scope, context, file) {
   go(function () {
     t.ensureBlock(node);
     return node.body.body;

lib/6to5/transformation/transformers/_block-hoist.js

@@ -1,4 +1,6 @@
-var useStrict = require("./use-strict");
+"use strict";
+
+var useStrict = require("../helpers/use-strict");
 var _         = require("lodash");
 
 // Priority:
@@ -12,13 +14,13 @@ exports.BlockStatement =
 exports.Program = {
   exit: function (node) {
     var hasChange = false;
-    for (var i in node.body) {
+    for (var i = 0; i < node.body.length; i++) {
       var bodyNode = node.body[i];
       if (bodyNode && bodyNode._blockHoist != null) hasChange = true;
     }
     if (!hasChange) return;
 
-    useStrict._wrap(node, function () {
+    useStrict.wrap(node, function () {
       var nodePriorities = _.groupBy(node.body, function (bodyNode) {
         var priority = bodyNode._blockHoist;
         if (priority == null) priority = 1;

lib/6to5/transformation/transformers/_declarations.js

@@ -1,14 +1,18 @@
-var useStrict = require("./use-strict");
+"use strict";
+
+var useStrict = require("../helpers/use-strict");
 var t         = require("../../types");
 
 exports.secondPass = true;
 
 exports.BlockStatement =
 exports.Program = function (node) {
+  if (!node._declarations) return;
+
   var kinds = {};
   var kind;
 
-  useStrict._wrap(node, function () {
+  useStrict.wrap(node, function () {
     for (var i in node._declarations) {
       var declar = node._declarations[i];
 

lib/6to5/transformation/transformers/_module-formatter.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var transform = require("../transform");
 
 exports.ast = {

lib/6to5/transformation/transformers/es6-arrow-functions.js

@@ -1,3 +1,5 @@
+"use strict";
+
 var t = require("../../types");
 
 exports.ArrowFunctionExpression = function (node) {