debounce.js

debounce.js

function debounce(func, wait = 20, options) {
	options = Object.assign({
		leading: false,
		trailing: true,
		throttle: false
	}, options);

	let timeout, isWaiting = false;

	return function debounced(...args) {
		if (!timeout && options.leading) func.apply(this, args);
		if (timeout) isWaiting = true;
		if (timeout && !options.throttle) {
			clearTimeout(timeout);
			timeout   = null;
			isWaiting = false;
		}
		if(!isWaiting){
			timeout = setTimeout(() => {
				if(options.trailing || (options.throttle && isWaiting)) func.apply(this, args);
				let wasWaiting = isWaiting;
				timeout = null;
				isWaiting = false;
				if(options.throttle && wasWaiting) debounced(...args);
			}, wait);
		}
	}
}