React+Typescript implements countdown hook method

import { useEffect, useRef } from 'react'

/**
 * interTerval hooks component* @param fn execution function* @param delay time* @param options immediate When true, execute the fn function immediately and then execute the timer*/
function useInterval(
  fn: () => void,
  delay: number | null | undefined,
  options?: {
    immediate?: boolean
  }
): void {
  const immediate = options?.immediate
  const timerRef = useRef<() => void>()

  timerRef.current = fn

  useEffect(() => {
    if (delay === undefined || delay === null) {
      return
    }
    if (immediate) {
      timerRef.current?.()
    }
    const timer = setInterval(() => {
      timerRef.current?.()
    }, delay)
    return () => {
      clearInterval(timer)
    }
  }, [delay])
}

export default useInterval

import { useState, useEffect, useRef, useMemo } from 'react'
import { useInterval } from './'

interface ITime {
  /** Current time */
  currentTime?: number
  /** End time */
  endTime?: number
  /** Another way, instead of passing the current time and end time, directly pass the time difference*/
  differTime?: number
}

interface ICbTime {
  d: number
  h: number
  m: number
  s: number
}

/**
 * Countdown hooks
 * @param options time object* @param cb callback function executed when countdown is completed* @param noImmediate whether to execute the callback immediately when the time passed in meets the callback execution conditions, the default is false*/
function useCountDown(
  options: ITime,
  cb?: () => void,
  noImmediate?: boolean
): ICbTime {
  const { currentTime = 0, endTime = 0, differTime = 0 } = options
  const [diffTime, setDiffTime] = useState(0)
  /** The time when the component receives the parameter*/
  const entryTime = useRef<number>(0)
  /** The time difference required by the current countdown*/
  const maxTime = useRef<number>(0)
  /** Is it possible to execute callback? */
  const isImplementCb = useRef(false)

  useEffect(() => {
    if (!isImplementCb.current) {
      isImplementCb.current = true
    }
    if ((currentTime > 0 && endTime > 0) || differTime > 0) {
      entryTime.current = new Date().getTime()
      maxTime.current = differTime > 0 ? differTime : endTime - currentTime
      if (maxTime.current <= 0 && noImmediate) {
        isImplementCb.current = false
      }
      setDiffTime(maxTime.current)
    }
  }, [currentTime, endTime, differTime])

  useInterval(
    () => {
      const curtTimes = new Date().getTime()
      const TimeDifference = curtTimes - entryTime.current
      setDiffTime(maxTime.current - TimeDifference)
    },
    diffTime <= 0 ? null : 1000
  )

  const timeObj = useMemo(() => {
    const time = diffTime > 0 ? diffTime / 1000 : 0
    const d = Math.floor(time / (24 * 60 * 60))
    const h = Math.floor((time / (60 * 60)) % 24)
    const m = Math.floor((time / 60) % 60)
    const s = Math.ceil(time % 60)

    if (diffTime <= 0 && isImplementCb.current) {
      /**
       * setTimeout is used to solve the react error problem:
       * annot update during an existing state transition (such as within `render`).
       * Render methods should be a pure function of props and state.
       */
      setTimeout(() => {
        cb?.()
      }, 0)
    }
    return { d, h, m, s }
  }, [diffTime])

  return timeObj || ({} as ICbTime)
}

export default useCountDown

  const TimeArea = () => {
    const { d, h, m, s } = useCountDown(
      {
        currentTime: 1631262176333,
        endTime: 1831062176333
      },
      () => {
        alert('Countdown ends')
      }
    )
    return (
      <div style={{ width: '200px', height: '200px' }}>
        {d} days until task end<i>{h < 10 ? '0' + h : h}</i>:
        <i>{m < 10 ? '0' + m : m}</i>:<i>{s < 10 ? '0' + s : s}</i>
      </div>
    )
  }