Added --delete-dir-on-start option for babel (#6187)

* added --delete-dir-on-start option 

added --delete-dir-on-start-option to delete dir on start of compilation to remove deleted files from the orignial files from the --out-dir

* added option --delete-dir-on-start

added --delete-dir-on-start that option will delete the --out-dir before the compilation of code to remove the deleted files from the source from the out directory

* added --delete-dir-on-start option

added --delete-dir-on-start-option to delete dir on start of compilation to remove deleted files from the orignial files from the --out-dir

* bug removed deleting the correct dir

in the previous code, the source dir was deleted each time rather than deleting the out dir

* Remove shorthand

* Prevent babel-cli option from reaching babel-core

* Lint

packages/babel-cli/src/babel/dir.js

@@ -63,6 +63,9 @@ export default function(commander, filenames, opts) {
     if (stat.isDirectory(filename)) {
       const dirname = filename;
 
+      if (commander.deleteDirOnStart) {
+        util.deleteDir(commander.outDir);
+      }
       util.readdir(dirname).forEach(function(filename) {
         const src = path.join(dirname, filename);
         handleFile(src, filename);

packages/babel-cli/src/babel/index.js

@@ -147,6 +147,10 @@ commander.option(
   "When compiling a directory copy over non-compilable files",
 );
 commander.option("-q, --quiet", "Don't log anything");
+commander.option(
+  "--delete-dir-on-start",
+  "Delete's the out directory before compilation",
+);
 /* eslint-enable max-len */
 
 commander.version(pkg.version + " (babel-core " + version + ")");
@@ -192,6 +196,9 @@ if (commander.watch) {
 if (commander.skipInitialBuild && !commander.watch) {
   errors.push("--skip-initial-build requires --watch");
 }
+if (commander.deleteDirOnStart && !commander.outDir) {
+  errors.push("--delete-dir-on-start requires --out-dir");
+}
 
 if (errors.length) {
   console.error(errors.join(". "));
@@ -216,6 +223,7 @@ delete opts.outDir;
 delete opts.copyFiles;
 delete opts.quiet;
 delete opts.configFile;
+delete opts.deleteDirOnStart;
 
 // Commander will default the "--no-" arguments to true, but we want to leave them undefined so that
 // babel-core can handle the default-assignment logic on its own.

packages/babel-cli/src/babel/util.js

@@ -58,6 +58,22 @@ export function compile(filename, opts) {
   }
 }
 
+export function deleteDir(path) {
+  if (fs.existsSync(path)) {
+    fs.readdirSync(path).forEach(function(file) {
+      const curPath = path + "/" + file;
+      if (fs.lstatSync(curPath).isDirectory()) {
+        // recurse
+        deleteDir(curPath);
+      } else {
+        // delete file
+        fs.unlinkSync(curPath);
+      }
+    });
+    fs.rmdirSync(path);
+  }
+}
+
 function toErrorStack(err) {
   if (err._babel && err instanceof SyntaxError) {
     return `${err.name}: ${err.message}\n${err.codeFrame}`;