如何实现一个能立即执行，且可以取消的节流

[inkjuncom]

function throttle(fn, delay) {
  let timer = null
  let lastTime = 0

  const throttled = function (...args) {
    const now = Date.now()

    if (now - lastTime >= delay) {
      lastTime = now
      fn.apply(this, args)
    }

    clearTimeout(timer)
    timer = setTimeout(() => {
      lastTime = 0
    }, delay)
  }

  throttled.cancel = function () {
    clearTimeout(timer)
    lastTime = 0
    timer = null
  }

  return throttled
}