s008-手写函数节流★★

function throttle(fn,delay = 100) {
  let timer = null;

  return function() {
    let ctx = this;
    if(timer) {
      return
    }
      timer = setTimeout(() => {
          fn.apply(ctx,arguments)
          timer = null;
      },delay)
  }
}

div1.addEventListener('drag',throttle(function(e) {
    console.log(e.offsetX)
},200))

function throttle(fn,delay) {
  let timer = null;
  let start = Date.now();
  return function() {
    let nowTime = Date.now();
    let left = delay - (nowTime - start);
    let context = this;
    let args = arguments;
    clearTimeout(timer);
    if(left <= 0) {
      fn.apply(context,agrs)
      start = Date.now();
    } else {
      timer = setTimeout(fn,left)
    }
  }
}

function throttle(fn, delay){
    let that = this
    let lastTime = 0
    return function() {
        let nowTime = new Date().getTime()
        if(nowTime - lastTime < delay) return // 两次时间间隔比设定的delay则return
        let arg = arguments // 此处为fn函数的参数
        fn.apply(that, arg)
        lastTime = nowTime // 把当前时间赋值给lastTime
    }
}



function test(a,b) {
    console.log(a,b)
}

let throttleTest = throttle(test, 1000)

window.onscroll = function(e) {
    throttleTest(1,2)
}