fix: fix cross origin workers

Author: Loïc Mangeonjean

src/tools/crossOriginWorker.ts

@@ -2,14 +2,39 @@
  * Cross origin workers don't work
  * The workaround used by vscode is to start a worker on a blob url containing a short script calling 'importScripts'
  * importScripts accepts to load the code inside the blob worker
+ * Copied from https://github.com/jantimon/remote-web-worker/blob/main/src/index.ts
  */
-class CrossOriginWorker extends Worker {
-  constructor (url: string | URL, options: WorkerOptions = {}) {
-    const fullUrl = new URL(url, window.location.href).href
-    const js = options.type === 'module' ? `import '${fullUrl}';` : `importScripts('${fullUrl}');`
-    const blob = new Blob([js], { type: 'application/javascript' })
-    super(URL.createObjectURL(blob), options)
+export class Worker extends window.Worker {
+  constructor (scriptURL: string | URL, options?: WorkerOptions) {
+    const url = String(scriptURL)
+    super(
+      // Check if the URL is remote
+      url.includes('://') && !url.startsWith(location.origin)
+        // Launch the worker with an inline script that will use `importScripts`
+        // to bootstrap the actual script to work around the same origin policy.
+        ? URL.createObjectURL(
+          new Blob(
+            [
+                // Replace the `importScripts` function with
+                // a patched version that will resolve relative URLs
+                // to the remote script URL.
+                //
+                // Without a patched `importScripts` Webpack 5 generated worker chunks will fail with the following error:
+                //
+                // Uncaught (in promise) DOMException: Failed to execute 'importScripts' on 'WorkerGlobalScope':
+                // The script at 'http://some.domain/worker.1e0e1e0e.js' failed to load.
+                //
+                // For minification, the inlined variable names are single letters:
+                // i = original importScripts
+                // a = arguments
+                // u = URL
+                `importScripts=((i)=>(...a)=>i(...a.map((u)=>''+new URL(u,"${url}"))))(importScripts);importScripts("${url}")`
+            ],
+            { type: 'text/javascript' }
+          )
+        )
+        : scriptURL,
+      options
+    )
   }
 }
-
-export { CrossOriginWorker as Worker }