手写一个事件监听节流函数

节流（throttle） 就是说在短时间内，如果快速重复的点击，无法执行请求

<button id="btn"></button>
<script>
  function throttle(fn,delay){
    let timer;
    return function(){
      let self = this
      if(timer) return;
      timer = setTimeout(()=>{
        fn.apply(self,arguments)
        timer = null
      },delay)
    }
  }
  function fn(){
    console.log('测试节流')
  }
  document.querySelector("#btn").addEventListener('click',throttle(fn,1000))
</script>

立即执行

    //防抖(合并版)
    function debounce_merge(fn, wait = 500, isImmediate = false) {
      var timerId = null;
      var flag = true;
      return function () {
        var context = this
        var args = arguments
        if(timerId) return false;
        if (isImmediate) {
          if (flag) {
            fn.apply(context, args)
            flag = false
          }
          timerId = setTimeout(function () {
            flag = true
          }, wait)
        } else {
          timerId = setTimeout(function () {
            fn.apply(context, args)
          }, wait)
        }
      }
    }