# 防抖和节流

function debounce(fn, delay) {
  let timer
  return () => {
    if (timer) {
      clearTimeout(timer)
    }
    timer = setTimeout(() => {
      fn()
      timer = null
    }, delay)
  }
}

function throttle(fn, delay) {
  let timer
  return () => {
    if (timer) return
    timer = setTimeout(() => {
      fn()
      timer = null
    }, delay)
  }
}