防抖函数和节流函数

防抖函数

function debounce(fn, delay = 200) {
  let timer
  return function(...args) {
    if (timer) {
      clearTimeout(timer)
      timer = null
    }
    timer = setTimeout(() => {
      fn.apply(this, args)
      clearTimeout(timer)
      timer = null
    }, delay)
  }
}

节流函数

function throttle(fn, delay = 200) {
  let flag = true
  return function(...args) {
    if(!flag) {
      return
    }
    flag = false
    let timer = setTimeout(() => {
      fn.apply(this, args)
      flag = true
      clearTimeout(timer)
    }, delay)
  }
}