节流函数 ​

function coloring() {
  let r = Math.floor(Math.random() * 255)
  let g = Math.floor(Math.random() * 255)
  let b = Math.floor(Math.random() * 255)
  document.body.style.backgroundColor = `rgb(${r},${g},${b})`
}
function throttle(fn, delay) {
  let pre = 0
  return function () {
    let now = new Date()
    if (now - pre > delay) {
      fn.apply(this, arguments)
      pre = now
    }
  }
}
window.addEventListener('resize', throttle(coloring, 3000))

function coloring() {
  let r = Math.floor(Math.random() * 255)
  let g = Math.floor(Math.random() * 255)
  let b = Math.floor(Math.random() * 255)
  document.body.style.backgroundColor = `rgb(${r},${g},${b})`
}
function throttle(fn, delay) {
  let pre = 0
  return function () {
    let now = new Date()
    if (now - pre > delay) {
      fn.apply(this, arguments)
      pre = now
    }
  }
}
window.addEventListener('resize', throttle(coloring, 3000))