请排好队，一个一个的来 --- 基于Promise.all()实现并发控制

const p = Promise.all([p1, p2, p3]);

  const requestsLimit = (list, limit, asyncHandle) => {
    return new Promise(resolve => {
      let _limit = limit;
      let recordList = []; // 记录异步操作
      let index = 0;
      let listCopy = [].concat(list);
      let asyncList = []; // 正在进行的所有并发异步操作


      const asyncFunc = () => {
        while(_limit--) {
          const data = listCopy.shift()
          if (data) asyncList.push(asyncHandle(data, index++)); 
        }
        
        Promise.all(asyncList).then(response => {
          // 监听并记录每一次请求的结果
          recordList = recordList.concat(response.filter(item => item));


          if (listCopy.length !== 0) {
            _limit = limit;
            asyncList = [];
            asyncFunc() // 数组还未迭代完，递归继续进行迭代
          } else {
            // 所有并发异步操作都完成后，本次并发控制迭代完成，返回记录结果
            resolve(recordList)
          }
        })
      }


      asyncFunc()
    })
  }


  var dataLists = [1,2,3,4,5,6,7,8];
  
  requestsLimit(dataLists, 3, (item, index) => {
    return new Promise(resolve => {
      // 执行异步处理
      setTimeout(() => {
        // 筛选异步处理的结果
        console.log(index)
        if (item % 2 === 0) resolve({ item, index })
        else resolve()
      }, Math.random() * 5000)  
    });
  }).then(response => {
    console.log('finish', response)
  })