Merge pull request facebook#4014 from viankakrisna/enable-manifest-plugin-on-dev

enable manifest plugin on dev

Author: Jack Zhao

packages/react-scripts/config/webpack.config.dev.js

@@ -20,6 +20,7 @@ const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
 const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
 const getClientEnvironment = require('./env');
 const paths = require('./paths');
+const ManifestPlugin = require('webpack-manifest-plugin');
 
 // Webpack uses `publicPath` to determine where the app is being served from.
 // In development, we always serve from the root. This makes config easier.
@@ -376,6 +377,13 @@ module.exports = {
     // https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
     // You can remove this if you don't use Moment.js:
     new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
+    // Generate a manifest file which contains a mapping of all asset filenames
+    // to their corresponding output file so that tools can pick it up without
+    // having to parse `index.html`.
+    new ManifestPlugin({
+      fileName: 'asset-manifest.json',
+      publicPath: publicPath,
+    }),
   ],
 
   // Some libraries import Node modules but don't use them in the browser.