AsyncTimeout: Now handles async functions for `thing` correctly. Improved `timeout_example(_timeout, cancel)` (+ `Cancellation` class for async cancellations). Added `try_example(time)` which runs the default example and cancels after `time`, returning the value or error in an object containing either `{ value: true }` or `{ error: <caught error> }` when awaited.

Added AsyncTimeout.await_timeout(time): Returns a promise that resolves when `time` has passed. No value is returned from this promise.

Added AsyncTimeout.await_interval(time): Returns an async iterator that yields after `time` has passed. No value is yielded from this async iterator.

(These helper functions are essentially the same as `new AsyncTimeout(()=>{}, time).[timeout/interval]()`.)

Fortune for async-timeout-js's current commit: Middle blessing − 中吉

asynctimeout.js

@@ -1,3 +1,13 @@
+
+const is_promise = obj => !!obj && (typeof obj === 'object' || typeof obj === 'function') && typeof obj.then === 'function';
+
+const fire_and_forget = (a, on_error) => {
+	(async () => {
+		try {
+			await a();
+		} catch(e) { if(on_error) on_error(e); else throw(e); }
+	})();
+};
 /// An async wrapper around `setTimeout()` and `setInterval()`. 
 ///
 /// # `setTimeout()`
@@ -15,43 +25,128 @@
 /// See `examples` below.
 function AsyncTimeout(thing, interval)
 {
-	function isPromise(obj) {
-	  return !!obj && (typeof obj === 'object' || typeof obj === 'function') && typeof obj.then === 'function';
-	}
-
-	async function _call(t)
-	{
-		if(isPromise(t)) return await t(arguments);
-		else await (async () => {});
-		return t(arguments);
-	}
-
 	this.timeout = () => new Promise((resolve, reject) => {
 		setTimeout(() => {
-			try {
-				_call(thing).then(resolve); //XXX: This design doesn't work, we'll need to go back to the drawing board with this function for this to work... The exception won't propagate here, so...
-			} catch(e) { reject(e); }
+			const eval_thing = () => {
+				try {
+					return thing();
+				} catch(e) { reject(e); }
+			};
+			const rv = eval_thing();
+			if(is_promise(rv)) fire_and_forget(async () => resolve(await rv), reject);
+			else resolve(rv);
 		}, interval);
 	});
 	this.interval = async function*() {
 		while(true) {
 			yield await new Promise((resolve, reject) => {
+				const eval_thing = () => {
+					try {
+						return thing();
+					} catch(e) { reject(e); }
+				};
 				setTimeout(() => {
-					try { _call(thing).then(resolve); } catch(e) { reject(e); }
+					const irv = eval_thing();
+					if(is_promise(irv)) fire_and_forget(async() => resolve(await irv), reject);
+					else resolve(irv);
 				}, interval);
 			});
 		}
 	};
 }
 
-const example = async (_timeout) => {
+/// Return a promise that will resolve when the timeout `i` has completed. There is no value for this resolution.
+AsyncTimeout.await_timeout = (i) => new AsyncTimeout(() => {}, i).timeout();
+/// Return an async iterator that will resolve the next iteration every `i`. There is no value for these yielded resolutions.
+AsyncTimeout.await_interval = (i) => new AsyncTimeout(() => {}, i).interval();
+
+/// Cancellation token source for `timeout_example`
+function Cancellation() { 
+	let tokens = [];
+
+	this.cancel_after_interrupt = (sig) => new Promise(resolve => {
+		sig = sig || 'SIGINT';
+		process.on(sig, () => { 
+			//console.log(`>>> Received signal ${sig}`);
+			resolve(sig || "<signal>");
+		});
+	});
+
+
+	this.cancel_after_invoke = () => new Promise(resolve => {
+		tokens.push(resolve);
+	});
+
+	this.cancel_invoke = (value) => tokens.shift()(value || "<invoked>");
+}
+
+/// Run the timeout example
+const timeout_example = async (_timeout, cancelAfter) => {
 	_timeout = _timeout || 100;
+	let cancel = false;
+
+	const canceller = new Promise(resolve => {
+		if(is_promise(cancelAfter)) (async () => {
+			resolve(cancel = ((await cancelAfter) || true));
+		})();
+		else if(cancelAfter && cancelAfter > 0) setTimeout(() => resolve(cancel = true), cancelAfter);
+		else resolve(false);
+	});
 
-	// Wait 100 then alert "hi"
+	// Wait _timeout then alert "hi"
 	console.log(await (new AsyncTimeout(() => "hi", _timeout)).timeout());
 
-	// Continuously wait 100 then alert "hi"
-	for await (const value of new AsyncTimeout(() => "hi forever", _timeout).interval()) { console.log(value); }
+	// Wait _timeout then call then await this async lambda, then print its result.
+	console.log(await (new AsyncTimeout(async () => {
+		console.log("> Hi starting promise...");
+		await AsyncTimeout.await_timeout(_timeout);
+		console.log(">> Hi inside promise!");
+		await AsyncTimeout.await_timeout(_timeout);
+		console.log("> Hi ending promise...");
+		return "hi, from async lambda!";
+	}, _timeout)).timeout());
+
+	// Wait _timeout as with this async lambda which uses `.interval()` producing the result `(_timeout / 10) || 10` times.
+	console.log(await (new AsyncTimeout(async () => {
+		let i=0;
+		const len = (_timeout / 10) || 10;
+		for await (const value of AsyncTimeout.await_interval(_timeout)) {
+			console.log(`[al]: iteration ${i}`);
+			i+=1;
+			if(cancel) throw "Operation cancelled.";
+			else if(i == len) return `Hi from async lambda containing iterator!, Completed ${i} iterations`;
+		}
+	}, _timeout)).timeout());
+
+	// Wait _timeout as interval running at most `(_interval / 10) || 10` times
+	console.log(await (async () => {
+		let i=0;
+		const len = (_timeout / 10) || 10;
+		for await (const value of new AsyncTimeout(async () => {
+			console.log(`i > Waiting ${_timeout * 2}`);
+			await AsyncTimeout.await_timeout(_timeout * 2);
+			console.log(`i > Returning ${i} as iteration value.`);
+			return `${i}`;
+		}, _timeout).interval()) { 
+			console.log(`!i >>> Iteration ${i}`);
+			i += 1;
+			if(cancel) throw "Operation cancelled.";
+			else if(i == len) return value;
+		}
+	})());
+
+	// Continuously wait _timeout then alert "hi forever", until `cancelAfter` is reached (if it is)
+	for await (const value of new AsyncTimeout(() => "hi forever", _timeout).interval()) { if(cancel) break; console.log(value); }
+
+	// Return `true` if cancelled (or, if `cancelAfter` was a promise that returned a truthy value, that resolved value); `false` if not (should never happen)
+	return await canceller;
 };
 
+/// Run the timeout example, catching an error if there is one thrown (usually on cancellation.)
+const try_example = async (time) => { 
+	try { return { value: await timeout_example(null, time) }; }
+	catch(e) { console.log(`Error! ${e}`); return {error: e}; } 
+};
 
+//try_example(2500); // Error! Operation cancelled. -> `{ error: "Operation cancelled." }`
+//try_example(5000); // -> `{ value: true }`