JavaScript实现可终止轮询请求的方法【java基础】【Js面试】

目录

• 什么是轮询请求？
• 轮询的要点
• setInterval的问题
• 实现轮询
• 准备工作
• 基础版
• 进阶版
• 最终版

// 成功
{
    "code": 0,
    "msg": "成功"
}
// 查询中
{
    "code": -1,
    "msg": "结果查询中"
}
// 失败
{
    "code": 1,
    "msg": "返回结果失败"
}

  
    
    
    
    
  
  
    开始
    停止
  

function myInterval(callback, interval = 2000) {
    let timerId
    const loop = async () => {
      callback()
      return (timer = setTimeout(loop, interval))
    }
    return {
      start: () => {
        loop()
      },
      stop: () => {
        console.log("停止执行")
        clearTimeout(timerId)
      }
    }
  }

function main() {
    count += 1
    console.log("执行：", count)
    if (count == 5) {
      count = 0
      intervalManager.stop()
    }
}

const loop = async () => {
  callback()
  return (timerId = setTimeout(() => {
    loop()
  }, interval))
}

// 可以自动停止的定时器
function myInterval(callback, interval = 2000) {
    let timer
    let isStop = false
    const stop = () => {
      console.log("停止")
      isStop = true
      clearTimeout(timer)
    }
    const start = () => {
      isStop = false
      loop()
    }
    const loop = async () => {
      callback()
      if (isStop) return
      return (timer = setTimeout(loop, interval))
    }
    return {
      start,
      stop
    }
  }

function main() {
    const flag = parseInt(Math.random() * 2) === 1
    console.log("flag", flag)
    return flag ? Promise.resolve() : Promise.reject()
}

function myInterval(callback, interval = 2000) {
    let timer
    let isStop = false
    const stop = () => {
      console.log("停止")
      isStop = true
      clearTimeout(timer)
    }
    const start = async () => {
      isStop = false
      await loop()
    }
    const loop = async () => {
      try {
        await callback(stop)
      } catch (err) {
        console.error("轮询出错：", err)
        throw new Error("轮询出错：", err)
      }
      if (isStop) return
      return (timer = setTimeout(loop, interval))
    }
    return {
      start,
      stop
    }
  }

let count = 0
function main(stop) {
    count += 1
    console.log("count：", count)
    if (count == 5) {
      stop()
    }
}