fix a regression with window resizing not triggering a canvas and viewport resize

Author: obiot

packages/melonjs/src/utils/function.ts

@@ -25,39 +25,29 @@ export function defer(
 /**
  * returns a function that, when invoked will only be triggered at most once during a given window of time
  * @param fn - the function to be throttled.
- * @param delay - the delay in ms
+ * @param [wait] - the delay in ms
  * @returns the function that will be throttled
  */
-export const throttle = <R, A extends any[]>(
-	fn: (...args: A) => R,
-	delay: number,
-): [(...args: A) => R | undefined, () => void] => {
-	let wait = false;
-	let timeout: undefined | number;
-	let cancelled = false;
-
-	return [
-		(...args: A) => {
-			if (cancelled) {
-				return undefined;
-			}
-			if (wait) {
-				return undefined;
-			}
-
-			const val = fn(...args);
-
-			wait = true;
-
-			timeout = window.setTimeout(() => {
-				wait = false;
-			}, delay);
-
-			return val;
-		},
-		() => {
-			cancelled = true;
-			clearTimeout(timeout);
-		},
-	];
+export const throttle = (fn: () => void, wait: number = 100) => {
+	let inThrottle: boolean,
+		lastFn: ReturnType<typeof setTimeout>,
+		lastTime: number;
+	return (...args: [] /* empty array */) => {
+		if (!inThrottle) {
+			fn.apply(this, args);
+			lastTime = Date.now();
+			inThrottle = true;
+		} else {
+			clearTimeout(lastFn);
+			lastFn = setTimeout(
+				() => {
+					if (Date.now() - lastTime >= wait) {
+						fn.apply(this, args);
+						lastTime = Date.now();
+					}
+				},
+				Math.max(wait - (Date.now() - lastTime), 0),
+			);
+		}
+	};
 };