POC - Handle when Worker is unsupported

src/index.js

@@ -1,4 +1,3 @@
-
 /** TODO:
  *	- pooling (+ load balancing by tracking # of open calls)
  *  - queueing (worth it? sortof free via postMessage already)
@@ -23,11 +22,34 @@ export default function workerize(code, options) {
 	if (typeof code==='function') code = `(${Function.prototype.toString.call(code)})(${exportsObjName})`;
 	code = toCjs(code, exportsObjName, exports) + `\n(${Function.prototype.toString.call(setup)})(self,${exportsObjName},{})`;
 	let url = URL.createObjectURL(new Blob([code])),
-		worker = new Worker(url, options),
-		term = worker.terminate,
 		callbacks = {},
 		counter = 0,
+		worker,
+		term,
 		i;
+
+	try {
+		worker = new Worker(url, options);
+		term = worker.terminate;
+	} catch (err) {
+		// TODO: How to indicate the fallback? console.warn? Property on the export?
+		// TODO: What's the right way to access the original exports?
+		const originalExports = new Function(code + `\nreturn ${exportsObjName}`)();
+		// TODO: Is this the full API? Do we need to add anything else?
+		worker = {
+			kill() {},
+			terminate() {},
+			expose(methodName) {
+				worker[i] = function() {
+					return Promise.resolve().then(() => originalExports[i]([].slice.call(arguments)));
+				};
+			},
+		};
+		// TODO: Extract to function since it's used below or fine as is?
+		for (i in exports) if (!(i in worker)) worker.expose(i);
+		return worker;
+	}
+
 	worker.kill = signal => {
 		worker.postMessage({ type: 'KILL', signal });
 		setTimeout(worker.terminate);