简易版防抖:
const debounce(fn,delay){
let timeOut;
return function(){
clearTimeout(timeout)
timeOut = setTimeOut(()=>{fn.apply(this,arguments)}),delay}
}
是否立即执行的防抖：
const debounce(fn,delay,ifNow){
let timeOut;
return function(){
if(timeOut)clearTimeout(timeout)
if(ifNow){
let callNow = !timeOut
timeOut = setTimeOut(()=>{timeOut = null},delay)
if(callNow){
fn.apply(this,arguments)}
}else{
timeOut = setTimeOut(()=>{fn.apply(this,arguments)}),delay}
}
}
