✍️ 防抖和节流

• 防抖 :

  /**
   * @description 防抖的立即执行版本
   */
  function debounce(fnc, delay, immediate) {
    let timer = null;
    return function () {
      let args = arguments,
        _this = this;
      if (timer) clearTimeout(timer);
      if (immediate) {
        let callNow = !timer; // callNew立即执行的时机为timer=null时
        timer = setTimeout(() => {
          timer = null;
        }, delay);
        if (callNow) fnc.call(_this, ...args);
      } else {
        timer = setTimeout(() => {
          fnc.call(_this, ...args);
        }, delay);
      }
    };
  }

• 节流 :

  function throttle(fnc, delay) {
    let timer = null;
    return function () {
      let _this = this,
        args = arguments;
      if (!timer) {
        timer = setTimeout(() => {
          fnc.call(_this, ...args);
          timer = null;
        }, delay);
      }
    };
  }