publicPath option

Added the ability to use a different public path when loading workers as a way to work around cross-origin policy issues.

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 test/expected
+.idea

README.md

@@ -149,6 +149,25 @@ self.postMessage({ foo: 'foo' })
 self.addEventListener('message', (event) => console.log(event))
 ```
 
+
+## Cross-origin policy workarounds
+
+Note that cross-origin policies for these worker objects still apply, so if your webpack assets are not hosted in the
+same origin as your application (including if you're loading them through the webpack dev server), they may be blocked
+by your browser. There are two workarounds. Firstly, you can inline the worker as a blob with the `inline` parameter:
+
+``` javascript
+var MyWorker = require("worker?inline!./file.js");
+```
+
+Secondly, you may proxy the script request through your application by overriding the public path for worker files
+via the `publicPath` option (make sure to URL-encode the path if specifying through a query string):
+
+```javascript
+var MyWorker = require("worker?publicPath=%2Fworkers%2F!./file.js");
+```
+
+
 ### `Integrating with TypeScript`
 
 To integrate with TypeScript, you will need to define a custom module for the exports of your worker

index.js

@@ -9,7 +9,8 @@ const SingleEntryPlugin = require('webpack/lib/SingleEntryPlugin');
 const schema = require('./options.json');
 
 const getWorker = (file, content, options) => {
-  const workerPublicPath = `__webpack_public_path__ + ${JSON.stringify(file)}`;
+  const publicPath = options.publicPath ? JSON.stringify(options.publicPath) : '__webpack_public_path__';
+  const workerPublicPath = `${publicPath} + ${JSON.stringify(file)}`;
   if (options.inline) {
     const createInlineWorkerPath = JSON.stringify(`!!${path.join(__dirname, 'createInlineWorker.js')}`);
     const fallbackWorkerPath = options.fallback === false ? 'null' : workerPublicPath;

options.json

@@ -9,6 +9,9 @@
     },
     "fallback": {
       "type": "boolean"
+    },
+    "publicPath": {
+      "type": "string"
     }
   },
   "additionalProperties": false

test/fixtures/public-path-override/entry.js

@@ -0,0 +1 @@
+const Worker = require('./worker.js');

test/fixtures/public-path-override/worker.js

@@ -0,0 +1 @@
+// named worker test mark

test/index.js

@@ -226,4 +226,26 @@ describe('worker-loader', () => {
       })
     );
   });
+
+  it('should use the publicPath option as the base URL if specified', () =>
+    makeBundle('public-path-override', {
+      module: {
+        rules: [
+          {
+            test: /worker\.js$/,
+            loader: '../index.js',
+            options: {
+              publicPath: '/some/proxy/',
+            },
+          },
+        ],
+      },
+    }).then((stats) => {
+      const assets = stats.compilation.assets;
+      const bundle = assets['bundle.js'];
+      const workerFile = Object.keys(assets).find(name => /worker\.js$/.test(name));
+
+      assert.notEqual(bundle._cachedSource.indexOf(`new Worker("/some/proxy/" + "${workerFile}")`), -1);
+    })
+  );
 });