SynchronousAsync.js

	const fetch = (url) => {
	return new Promise((resolve, reject) => {
	setTimeout(() => {
	console.log(url)
	switch(url.match(/\d[aA-zZ]$/)[0]) {
	case "1a":
	resolve({name: "Seb"})
	// or try this instead:
	// reject({error: "something went wrong while fetching " + url})
	break;
	case "1b":
	resolve({name: "Markbage"})
	}
	}, 1000)
	})
	}
	let cache = new Map();
	let pending = new Map();
	function fetchTextSync(url) {
	if (cache.has(url)) {
	return cache.get(url);
	}
	if (pending.has(url)) {
	throw pending.get(url);
	}
	let promise = fetch(url).then(
	obj => {
	pending.delete(url);
	cache.set(url, obj);
	},
	error => {
	pending.delete(url);
	throw error
	}
	)
	pending.set(url, promise);
	throw promise;
	}
	async function runPureTask(task) {
	for (;;) {
	try {
	return task();
	} catch (x) {
	if (x instanceof Promise) {
	await x;
	} else {
	throw x
	}
	}
	}
	}