Create @babel/plugin-syntax-top-level-await (#10573)

packages/babel-plugin-syntax-top-level-await/.npmignore

@@ -0,0 +1,3 @@
+node_modules
+*.log
+src

packages/babel-plugin-syntax-top-level-await/README.md

@@ -0,0 +1,19 @@
+# @babel/plugin-syntax-top-level-await
+
+> Allow parsing of top-level await in modules
+
+See our website [@babel/plugin-syntax-top-level-await](https://babeljs.io/docs/en/next/babel-plugin-syntax-top-level-await.html) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/plugin-syntax-top-level-await
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/plugin-syntax-top-level-await --dev
+```

packages/babel-plugin-syntax-top-level-await/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "@babel/plugin-syntax-top-level-await",
+  "version": "7.6.4",
+  "description": "Allow parsing of top-level await in modules",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-syntax-top-level-await",
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "@babel/helper-plugin-utils": "^7.0.0"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.0.0-0"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.4.4"
+  }
+}

packages/babel-plugin-syntax-top-level-await/src/index.js

@@ -0,0 +1,13 @@
+import { declare } from "@babel/helper-plugin-utils";
+
+export default declare(api => {
+  api.assertVersion(7);
+
+  return {
+    name: "syntax-top-level-await",
+
+    manipulateOptions(opts, parserOpts) {
+      parserOpts.plugins.push("topLevelAwait");
+    },
+  };
+});

packages/babel-preset-env/package.json

@@ -27,6 +27,7 @@
     "@babel/plugin-syntax-json-strings": "^7.2.0",
     "@babel/plugin-syntax-object-rest-spread": "^7.2.0",
     "@babel/plugin-syntax-optional-catch-binding": "^7.2.0",
+    "@babel/plugin-syntax-top-level-await": "^7.6.4",
     "@babel/plugin-transform-arrow-functions": "^7.2.0",
     "@babel/plugin-transform-async-to-generator": "^7.5.0",
     "@babel/plugin-transform-block-scoped-functions": "^7.2.0",

packages/babel-preset-env/src/available-plugins.js

@@ -6,6 +6,7 @@ export default {
   "syntax-json-strings": require("@babel/plugin-syntax-json-strings"),
   "syntax-object-rest-spread": require("@babel/plugin-syntax-object-rest-spread"),
   "syntax-optional-catch-binding": require("@babel/plugin-syntax-optional-catch-binding"),
+  "syntax-top-level-await": require("@babel/plugin-syntax-top-level-await"),
   "transform-async-to-generator": require("@babel/plugin-transform-async-to-generator"),
   "proposal-async-generator-functions": require("@babel/plugin-proposal-async-generator-functions"),
   "proposal-dynamic-import": require("@babel/plugin-proposal-dynamic-import"),

packages/babel-preset-env/src/index.js

@@ -65,11 +65,13 @@ export const getModulesPluginNames = ({
   transformations,
   shouldTransformESM,
   shouldTransformDynamicImport,
+  shouldParseTopLevelAwait,
 }: {
   modules: ModuleOption,
   transformations: ModuleTransformationsType,
   shouldTransformESM: boolean,
   shouldTransformDynamicImport: boolean,
+  shouldParseTopLevelAwait: boolean,
 }) => {
   const modulesPluginNames = [];
   if (modules !== false && transformations[modules]) {
@@ -95,6 +97,11 @@ export const getModulesPluginNames = ({
   } else {
     modulesPluginNames.push("syntax-dynamic-import");
   }
+
+  if (shouldParseTopLevelAwait) {
+    modulesPluginNames.push("syntax-top-level-await");
+  }
+
   return modulesPluginNames;
 };
 
@@ -165,6 +172,10 @@ function supportsDynamicImport(caller) {
   return !!(caller && caller.supportsDynamicImport);
 }
 
+function supportsTopLevelAwait(caller) {
+  return !!(caller && caller.supportsTopLevelAwait);
+}
+
 export default declare((api, opts) => {
   api.assertVersion(7);
 
@@ -225,6 +236,7 @@ export default declare((api, opts) => {
       modules !== "auto" || !api.caller || !api.caller(supportsStaticESM),
     shouldTransformDynamicImport:
       modules !== "auto" || !api.caller || !api.caller(supportsDynamicImport),
+    shouldParseTopLevelAwait: api.caller(supportsTopLevelAwait),
   });
 
   const pluginNames = filterItems(

packages/babel-preset-env/test/fixtures/top-level-await/supported/input.mjs

@@ -0,0 +1 @@
+await 0;

packages/babel-preset-env/test/fixtures/top-level-await/supported/options.json

@@ -0,0 +1,8 @@
+{
+  "caller": {
+    "name": "test-fixture",
+    "supportsStaticESM": true,
+    "supportsTopLevelAwait": true
+  },
+  "presets": ["env"]
+}

packages/babel-preset-env/test/fixtures/top-level-await/supported/output.mjs

@@ -0,0 +1 @@
+await 0;

packages/babel-preset-env/test/fixtures/top-level-await/unsupported/input.mjs

@@ -0,0 +1 @@
+await 0;

packages/babel-preset-env/test/fixtures/top-level-await/unsupported/options.json

@@ -0,0 +1,9 @@
+{
+  "caller": {
+    "name": "test-fixture",
+    "supportsStaticESM": true,
+    "supportsTopLevelAwait": false
+  },
+  "presets": ["env"],
+  "throws": "Can not use keyword 'await' outside an async function (1:0)"
+}