防抖函数

    let fn = (x) => {
      console.log("start " + x);
    };    
    let timer = null;
    function debounce(time, fn, ...argus) {
      if (timer) {
        window.clearTimeout(timer);
      }
      timer = setTimeout(() => {
        fn.apply(null, argus);
        timer = false;
      }, time);
    }