2805. 自定义间隔

2805. 自定义间隔

type IntervalFn = () => void

interface CustomIntervalMap {
  [id: number]: boolean
}

// 用于存储每个定时器的“取消”状态
const intervalMap: CustomIntervalMap = {}
let uid = 0

/**
 * 模拟 setInterval，支持 clear
 * @param fn 执行的函数
 * @param delay 首次延迟
 * @param period 周期间隔
 * @returns id 可用于 clear
 */
function customInterval(fn: IntervalFn, delay: number, period: number): number {
  const id = ++uid
  intervalMap[id] = false
  let count = 0

  const cb = () => {
    if (intervalMap[id]) return // 被 clear 掉
    fn()
    setTimeout(cb, count++ * period + delay)
  }

  setTimeout(cb, count++ * period + delay)
  return id
}

/**
 * 清除定时器
 * @param id 定时器 id
 */
function customClearInterval(id: number): void {
  intervalMap[id] = true
}