Expose a worker override from the ESM entry

src/index.esm.ts

@@ -173,7 +173,7 @@ export {setRTLTextPlugin, getRTLTextPluginStatus} from './source/rtl_text_plugin
 export {setSdkInfo} from './util/mapbox';
 export {addTileProvider} from './source/tile_provider';
 export {prewarm, clearPrewarmedResources} from './util/worker_pool_factory';
-export {setWorkerUrl} from './util/worker_class';
+export {setWorkerUrl, setWorkerClass, setWorkerFactory} from './util/worker_class';
 export {getWorkerCount, setWorkerCount} from './util/worker_pool';
 export {setAccessToken, setBaseApiUrl, setMaxParallelImageRequests, getDracoUrl, setDracoUrl, getMeshoptUrl, setMeshoptUrl, getBuildingGenUrl, setBuildingGenUrl} from './util/config';
 

src/util/web_worker_esm_npm.ts

@@ -5,6 +5,11 @@ import WorkerClass from './worker_class';
 // its dependencies into a separate chunk. Also works when self-hosted
 // same-origin without a bundler.
 export function createWorker(): Worker {
+    if (WorkerClass.workerFactory) return WorkerClass.workerFactory();
+
+    // eslint-disable-next-line new-cap
+    if (WorkerClass.workerClass != null) return new WorkerClass.workerClass();
+
     if (WorkerClass.workerUrl) {
         return new Worker(WorkerClass.workerUrl, {type: 'module'});
     }

src/util/worker_class.ts

@@ -3,12 +3,14 @@ import type {Class} from '../types/class';
 type WorkerState = {
     workerUrl: string;
     workerClass: Class<Worker> | null;
+    workerFactory: (() => Worker) | null;
     workerParams?: WorkerOptions; // Internal, test-only: extra options passed to `new Worker()`
 };
 
 const WorkerClass: WorkerState = {
     workerUrl: '',
     workerClass: null,
+    workerFactory: null,
     workerParams: undefined,
 };
 
@@ -24,4 +26,37 @@ export function setWorkerUrl(url: string) {
     WorkerClass.workerUrl = url;
 }
 
+/**
+ * Sets a constructor used to create the WebWorker. Must be set once, before the
+ * first `new Map(...)`. Counterpart to `mapboxgl.workerClass` on the default
+ * bundle, and takes precedence over {@link setWorkerUrl}.
+ *
+ * Bundlers that only rewrite the `new Worker(new URL(...), ...)` pattern in the
+ * application's own sources — Angular's esbuild-based builder, for example —
+ * never see the equivalent expression inside this package and therefore emit no
+ * worker chunk for it. Passing a constructor lets the application spell that
+ * pattern out itself and hand the resulting worker back.
+ *
+ * @param {Class<Worker>} klass A constructor returning a WebWorker running the GL JS worker bundle.
+ */
+export function setWorkerClass(klass: Class<Worker> | null) {
+    WorkerClass.workerClass = klass;
+}
+
+/**
+ * Sets a function used to create the WebWorker. Must be set once, before the
+ * first `new Map(...)`. Takes precedence over {@link setWorkerClass} and
+ * {@link setWorkerUrl}.
+ *
+ * Serves the same purpose as {@link setWorkerClass}, in a shape that type-checks:
+ * an application that has to construct the worker itself can only return an
+ * instance, and a constructor returning an unrelated object cannot be expressed
+ * in TypeScript, so every `workerClass` caller ends up asserting the type.
+ *
+ * @param {Function} create A function returning a WebWorker running the GL JS worker bundle.
+ */
+export function setWorkerFactory(create: (() => Worker) | null) {
+    WorkerClass.workerFactory = create;
+}
+
 export default WorkerClass;