debounce和throttle

// 常用于window resize 或 scroll监听
function debounce(fn, wait) {
  wait = wait || 0
  let timerId

  return function () {
    let context = this
    let args = arguments

    if (timerId) {
      clearTimeout(timerId)

      timerId = null
    }
    timerId = setTimeout(function () {
      fn.apply(context, args)
    }, wait)
  }
}

// 常用于按钮提交 或 实时查询
function throttle(fn, threshhold) {
  let last, timer
  threshhold || (threshhold = 200)

  return function () {
    let context = this
    let args = arguments

    let now = +new Date()

    if ((last && now < last + threshhold)) {
      clearTimeout(timer)

      timer = setTimeout(function () {
        last = now
        fn.apply(context, args)
      }, threshhold)
    } else {
      last = now
      fn.apply(context, args)
    }
  }
}