format UglifyJs error

packages/react-dev-utils/README.md

@@ -220,6 +220,20 @@ compiler.plugin('done', function(stats) {
 });
 ```
 
+#### `formatBuildError(error: Object): String`
+
+Prettify some known build errors.
+Pass an Error object to log a prettified error message in the console
+
+```
+  const formatBuildError = require('react-dev-utils/formatBuildError')
+  try {
+    build()
+  } catch(e){
+    formatBuildError(e) // logs prettified message
+  }
+```
+
 #### `getProcessForPort(port: number): string`
 
 Finds the currently running process on `port`.

packages/react-dev-utils/formatBuildError.js

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+const get = require('lodash/get');
+const chalk = require('chalk');
+
+module.exports = function formatBuildError(err) {
+  const message = get(err, 'message');
+  const stack = get(err, 'stack');
+
+  // Add more helpful message for UglifyJs error
+  if (
+    stack &&
+    typeof message === 'string' &&
+    message.indexOf('from UglifyJs') !== -1
+  ) {
+    try {
+      const matched = /Unexpected token:(.+)\[(.+)\:(.+)\,(.+)\]\[.+\]/.exec(
+        stack
+      );
+      if (!matched) {
+        throw new Error(
+          "The regex pattern is not matched. Maybe UglifyJs changed it's message?"
+        );
+      }
+      const problemPath = matched[2];
+      const line = matched[3];
+      const column = matched[4];
+      console.log(
+        'Failed to minify the code from this file: \n\n',
+        chalk.yellow(`${problemPath} line ${line}:${column}`),
+        '\n'
+      );
+    } catch (ignored) {
+      console.log('Failed to minify the code.', err);
+    }
+    console.log(
+      'Please check your dependencies for any untranspiled es6 code and raise an issue with \n' +
+        'the author. \n' +
+        '\nIf you need to use the module right now, you can try placing the source in ./src \n' +
+        'and we will transpile it for you.'
+    );
+  } else {
+    console.log((message || err) + '\n');
+  }
+};

packages/react-dev-utils/package.json

@@ -18,13 +18,14 @@
     "crossSpawn.js",
     "eslintFormatter.js",
     "FileSizeReporter.js",
+    "formatBuildError.js",
     "formatWebpackMessages.js",
     "getProcessForPort.js",
     "inquirer.js",
     "InterpolateHtmlPlugin.js",
     "launchEditor.js",
-    "noopServiceWorkerMiddleware.js",
     "ModuleScopePlugin.js",
+    "noopServiceWorkerMiddleware.js",
     "openBrowser.js",
     "openChrome.applescript",
     "printHostingInstructions.js",

packages/react-scripts/scripts/build.js

@@ -34,6 +34,7 @@ const checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
 const formatWebpackMessages = require('react-dev-utils/formatWebpackMessages');
 const printHostingInstructions = require('react-dev-utils/printHostingInstructions');
 const FileSizeReporter = require('react-dev-utils/FileSizeReporter');
+const formatBuildError = require('react-dev-utils/formatBuildError');
 
 const measureFileSizesBeforeBuild = FileSizeReporter.measureFileSizesBeforeBuild;
 const printFileSizesAfterBuild = FileSizeReporter.printFileSizesAfterBuild;
@@ -93,7 +94,7 @@ measureFileSizesBeforeBuild(paths.appBuild)
     },
     err => {
       console.log(chalk.red('Failed to compile.\n'));
-      console.log((err.message || err) + '\n');
+      formatBuildError(err);
       process.exit(1);
     }
   );