JavaScriptにおける手ぶれ防止と節流

  ?    :     

//         
var debounce = (fn, wait, immediate = false) => {
	let timer, startTimeStamp = 0;
	let context, args;
 
	let run = (timerInterval)=>{
		timer = setTimeout(()=>{
			let now = (new Date()).getTime();
			let interval = now - startTimeStamp
			// the timer start time has been reset，so the interval is less than timerInterval
			if(interval < timerInterval){ 
				console.log('debounce reset', timerInterval-interval);
				startTimeStamp = now;
				run(timerInterval - interval);  // reset timer for left time 
			} else { //   wait       
				if(!immediate){
					fn.apply(context, args);
				}
				clearTimeout(timer);
				timer = null;
			}
			
		}, timerInterval);
	}
 
	return function(){
		context = this;
		args = arguments;
		let now = (new Date()).getTime();
		startTimeStamp = now; // set timer start time
 
		if(!timer){
			console.log('debounce set',wait);
			if(immediate) {
				fn.apply(context, args);
			}
			run(wait);    // last timer alreay executed, set a new timer
		}	
	}
}

//     
var throttling = (fn, wait, immediate) => {
	let timer, timeStamp = 0;
	let context, args;
 
	let run = () => {
		timer = setTimeout(()=>{
			if(!immediate){
				fn.apply(context,args);
			}
			clearTimeout(timer);
			timer = null;
		}, wait);
	}
 
	return function () {
		context = this;
		args = arguments;
		if(!timer){
			console.log("throttle, set");
			if(immediate){
				fn.apply(context,args);
			}
			run();
		} else {
			console.log("throttle, ignore");
		}
	}
 
}