节流与防抖

[dave-wind]

节流与防抖

function debounce(fn, num = 300) {
  let self, timer = null;
  return function () {
    self = this;
    if (timer) {
      clearTimeout(timer);
      timer = null;
    }
    timer = setTimeout(function () {
      fn.apply(self, arguments)
    }, num)
  }
}

function throttle(fn, delay = 300) {
  let lasttime, now, timer = null, self, args;
  const excute = function () {
    fn.apply(self, args);
    lasttime = now;
  }
  return function () {
    self = this;
    args = Array.prototype.slice.call(arguments);
    now = new Date().getTime();
    if (timer) {
      clearTimeout(timer);
      timer = null
    }
    if (lasttime) {
      const diff = delay - (now - lasttime);
      if (diff > 0) { // 操作非常频繁 就延迟执行
        timer = setTimeout(function () {
          excute()
        }, delay)
      } else {
        excute()
      }

    } else {
      excute()
    }
  }
}