yanan.wang/src/util.js

This is a toolset

/**
 * @method
 * @desc 防抖函数
 * @param {function} fn 执行的函数
 * @param {Number} delay 延迟时间
 * @param {Boolean} immediate 第一次是否立即执行
 * @param {Function} callback 回调函数
 */
function debounce(fn, delay, immediate = false , callback) {
  let isInvoke = true
  let timer = null;

  const foo = function(event) {
    return new Promise((resolve, reject) => {
      let result = null
      try {
        if(isInvoke && isInvoke) {
          result = fn.apply(this,[event])
          callback && callback(result)
          resolve(result)
          isInvoke = false
        } else {
          //有值得话定时器状态一定是启动
          if(timer) clearTimeout(timer)
          timer = setTimeout(() => {
            result = fn.apply(this,[event])
            callback && callback(result)
            resolve(result)
            timer = null
            isInvoke = false
          }, delay);
        }

      } catch (error) {
        reject(error)
      }

    })
  }
  //这里不要用this
  foo.cancel = function() {

    if(timer) {
      clearTimeout(timer);
      timer = null
    }

  }
  return foo
}

/**
 * @method
 * @desc 节流函数
 * @param {function} fn 执行的函数
 * @param {Number} delay
 * @param {Boolean} immediate 第一次是否立即执行
 * @param {Boolean} ending 最后一次是否执行
 */
function throttle(fn, delay, immediate = true, ending = true) {
  let timer = null;
  let isInvoke = true
  let startTime = 0
  function _throttle(event) {

    let nowTime = new Date().valueOf()
    return new Promise((resolve, reject) => {

      let waitTime = delay - (nowTime - startTime)
      //判断立即执行
      if(!immediate && startTime === 0) {
        startTime = nowTime
      }

      //基本节流实现
      if(waitTime <= 0) {
        resolve(fn.apply(this, [event]))
        timer && clearTimeout(timer)
        startTime = nowTime;
        timer = null
      }

      //尾部执行
      if(ending && !timer) {
        timer = setTimeout(() => {
          resolve(fn.apply(this, [event]))
          startTime = Date.now();
          timer = null
        }, waitTime);
      }
    })

  }

  return _throttle
}

module.exports = {
  throttle, debounce
}