inital #2

src/polyfill.ts

@@ -0,0 +1,43 @@
+import {RequestHandler} from 'express';
+import * as polyfillLibrary from 'polyfill-library';
+import {PolyfillFeatureList, PolyfillOptions} from 'polyfill-library';
+import {DefaultConfig, Logger, WaitForSync} from '.';
+import {spawn, Thread, Worker} from 'threads';
+import {WorkerFunction} from 'threads/dist/types/worker';
+
+const features = new WaitForSync<PolyfillFeatureList>();
+
+(async () => {
+	const worker = await spawn<WorkerFunction>(new Worker("./polyfill-worker"));
+	const feats = await worker() as PolyfillFeatureList;
+	await Thread.terminate(worker);
+	return feats;
+})()
+	.then(feats => {
+		feats["fetch"] = {};
+		Logger.debug("Polyfill analysed:", Object.keys(feats));
+		features.setData(feats);
+	})
+	.catch(err => features.setError(err));
+
+
+function getRouter(opts?: Partial<PolyfillOptions>): RequestHandler {
+	const options: Partial<PolyfillOptions> = {
+		minify: DefaultConfig.isProduction,
+		unknown: "polyfill",
+		...opts
+	}
+	return async (req, res) => {
+		const polyfillBundle = await polyfillLibrary.getPolyfillString({
+			...options,
+			uaString: req.header("user-agent"),
+			features: await features.resolve(),
+			stream: false,
+		});
+		res.setHeader('Content-Type', 'text/javascript');
+		res.send(polyfillBundle);
+	};
+}
+export const Polyfill = {
+	getRouter: getRouter,
+};