javascript debounce

debounce.js

/**
 * Debounce creates a FUNCTION that when invoked, delays invoking fn for wait milliseconds since
 * the last time it is called.
 *
 * @see https://gist.github.com/ZatsuneNoMokou/6d0af1783c348facde59c92c53a63b1f/617ccd3e858446983aa166b322ccb30319cf6dd8
 * @param {number} fn - function to call
 * @param {number} wait - duration in milliseconds
 * @param {number} maxWait - max duration in milliseconds before calling {@param fn}
 * @retun {function} a function that will wait {@param wait} milliseconds since it's last called to invoke {@param fn}.
 */
function debounce(fn, wait, maxWait=null) {
	let timeoutId = null,
		timeoutIdMax = null;

	return function() {
		const context = this, args = arguments;
		if (timeoutId !== null) self.clearTimeout(timeoutId);

		if (maxWait !== null && timeoutIdMax === null) {
			timeoutIdMax = self.setTimeout(function () {
				self.clearTimeout(timeoutId);
				timeoutId = timeoutIdMax = null;
				fn.apply(context, args);
			}, maxWait); // you want to make sure foo executes and timeoutId is cancelled
		}

		timeoutId = self.setTimeout(function() {
			self.clearTimeout(timeoutId);
			timeoutId = null;

			fn.apply(context, args);

			if (maxWait !== null && timeoutIdMax !== null){
				self.clearTimeout(timeoutIdMax);
				timeoutIdMax = null;
			}
		}, wait); // you want to make sure foo executes maxTimeoutId is cancelled
	};
}