Set jsonpFunction to prevent conflicts (facebook#5951)

Author: sibiraj-s

config/webpack.config.js

@@ -39,6 +39,8 @@ const getCacheIdentifier = require('react-dev-utils/getCacheIdentifier');
 // @remove-on-eject-end
 const postcssNormalize = require('postcss-normalize');
 
+const appPackageJson = require(paths.appPackageJson);
+
 // Source maps are resource heavy and can cause out of memory issue for large source files.
 const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';
 // Some apps do not need the benefits of saving a web request, so not inlining the chunk
@@ -189,6 +191,9 @@ module.exports = function(webpackEnv) {
               .replace(/\\/g, '/')
         : isEnvDevelopment &&
           (info => path.resolve(info.absoluteResourcePath).replace(/\\/g, '/')),
+      // Prevents conflicts when multiple Webpack runtimes (from different apps)
+      // are used on the same page.
+      jsonpFunction: `webpackJsonp${appPackageJson.name}`,
     },
     optimization: {
       minimize: isEnvProduction,
@@ -197,7 +202,7 @@ module.exports = function(webpackEnv) {
         new TerserPlugin({
           terserOptions: {
             parse: {
-              // we want terser to parse ecma 8 code. However, we don't want it
+              // We want terser to parse ecma 8 code. However, we don't want it
               // to apply any minification steps that turns valid ecma 5 code
               // into invalid ecma 5 code. This is why the 'compress' and 'output'
               // sections only apply transformations that are ecma 5 safe