// 节流是指:让其在第一次触发事件
// 防抖是指:让其在最后一次触发事件

// fn对应的时间处理函数，delay间隔时间，immediate第一次是否立即执行
// 防抖
const debounce = function(fn, delay, immediate) {
  let timer = null
  return function() {
    const that = this
    const arg = arguments
    if (timer) {
      clearTimeout(timer)
    }
    if (immediate) {
      const bool = !timer
      timer = setTimeout(() => {
        timer = null
      }, delay)
      if (bool) {
        fn.apply(that, arg)
      }
    } else {
      timer = setTimeout(() => {
        timer = null
        fn.apply(that, arg)
      }, delay)
    }
  }
}

// 节流
const throttle = function(fn, delay, immediate) {
  let timer = null
  return function() {
    const that = this
    const arg = arguments
    if (immediate) {
      if (!timer) {
        timer = setTimeout(() => {
          timer = null
        }, delay)
        fn.apply(that, arg)
      }
    } else {
      if (!timer) {
        timer = setTimeout(() => {
          timer = null
          fn.apply(that, arg)
        }, delay)
      }
    }
  }
}

export { debounce, throttle }