函数节流[throttle]
让函数保持在一个可接受的固定频率执行
let box=document.querySelector("#box")
let index=0;
function throttle(fn,interval=200,isStart=true){
let timer=0;
return function(...args){
if(timer){ return }
const _this=this;
isStart&&fn.apply(_this,args);
timer=setTimeout(()=>{
(!isStart)&&fn.apply(_this,args);
timer=0;
},interval)
}
box.onmousemove=throttle(function(e){
index++;
console.log("move",index)
},1000,true);
