js节流小案例

js节流小案例

  let flag = true;
    function throttled(fn, delay){
      if(!flag){
        return false
      }
      flag = false
      setTimeout(function(){
        fn()
        flag = true
      },delay)
    }
   /* 正常思路版
   function throttled(fn, delay) {
      let lastTime = null;
      return function (...args) {
        let now = Date.now();
        if (lastTime === null || now - lastTime > delay) {
          lastTime = now;
          return fn.apply(this, args);
        }
      };
    } */
    function showTop(){
      let scrollTop = document.body.scrollTop || document.documentElement.scrollTop
      console.log(scrollTop);
    }
    document.addEventListener('scroll',function(){
      throttled(showTop, 10000)
    })