Concurrent optimization request

//  Concurrent optimization 10 A request , At most can be executed at the same time 3 individual 
//  Input ：promise Array ,limit Parameters 
//  Storage  reqPool -  Concurrent pool 
//  Ideas ： Insert  +  perform 

function qpsLimit (requestPipe, limitMax=3) {
    
  let reqPool = []

  //  Insert requests into the concurrency pool 
  const add = () => {
    
    let req = requestPipe.shift()
    reqPool.push(req)
  }

  //  Execute the actual request 
  const run = () => {
    
    if (requestPipe.length === 0) return
    let finsh = Promise.race(reqPool)
    finsh.then(res => {
    
      let done = reqPool.indexOf(finsh)
      reqPool.splice(done, 1)
      add()
    })
    run()
  }

  while (reqPool.length < limitMax) {
    
    add()
  }
  run()
}