Made webpack respect NODE_PATH environment variable

Fixes: facebook#253

Author: Jimmy Miller

Diff for: config/env.js

@@ -14,6 +14,7 @@
 
 var REACT_APP = /^REACT_APP_/i;
 var NODE_ENV = JSON.stringify(process.env.NODE_ENV || 'development');
+var NODE_PATH = process.env.NODE_PATH || '';
 
 module.exports = Object
   .keys(process.env)
@@ -22,5 +23,6 @@ module.exports = Object
     env['process.env.' + key] = JSON.stringify(process.env[key]);
     return env;
   }, {
-    'process.env.NODE_ENV': NODE_ENV
+    'process.env.NODE_ENV': NODE_ENV,
+    'process.env.NODE_PATH': NODE_PATH
   });

Diff for: config/webpack.config.dev.js

@@ -68,6 +68,9 @@ module.exports = {
     publicPath: '/'
   },
   resolve: {
+    // This allows you to set a root for where webpack should look for modules.
+    // This enables you to use absolute imports from the root.
+    root: path.resolve(env['process.env.NODE_PATH']),
     // These are the reasonable defaults supported by the Node ecosystem.
     extensions: ['.js', '.json', ''],
     alias: {

Diff for: config/webpack.config.prod.js

@@ -63,6 +63,9 @@ module.exports = {
     publicPath: publicPath
   },
   resolve: {
+    // This allows you to set a root for where webpack should look for modules.
+    // This enables you to use absolute imports from the root.
+    root: path.resolve(env['process.env.NODE_PATH']),
     // These are the reasonable defaults supported by the Node ecosystem.
     extensions: ['.js', '.json', ''],
     alias: {