事件节流

  let last = 0 // 上次触发时间
  return (...args) => {
    const now = Date.now()
    if (now - last > delay) {
      last = now
      fn.apply(this, args)
    }
  }
}

// 测试
function task() {
  console.log('run task')
}
const throttleTask = throttle(task, 1000)
window.addEventListener('scroll', throttleTask)