防抖节流

    function throFun(){
        console.log(this)
        console.log('执行真正的函数')
    }

    var thro = debounce (throFun,1000);

    box.addEventListener('click' , function(){
        thro();
    })

    function debounce (method,time){
        let timer = null
        return function(){
            console.log('被触发')
            clearTimeout(timer)
            timer = setTimeout(()=>{
                method.apply(this,arguments)
            },time)
        }
    }


  function throttle (method,delay,immediate = true){
        let  prev = Date.now();
        let flag = true

        return function(){
            if(immediate && flag){
                method.apply(this,arguments)
                flag = false
                prev = Date.now();
            }
            console.log('被触发')
            let now = Date.now();
            if(now - prev >= delay){
                method.apply(this,arguments)
                prev = Date.now();
            }

        }
  }