concurrent.js

const p1 = new Promise(resolve => setTimeout(resolve, 300, 'first promise'))
const p2 = new Promise(resolve => setTimeout(resolve, 200, 'second promise'))
const p3 = new Promise(resolve => setTimeout(resolve, 700, 'third promise'))
const p4 = new Promise(resolve => setTimeout(resolve, 500, 'fourth promise'))
const p5 = new Promise(resolve => setTimeout(resolve, 900, 'fifth promise'))

function concurrentCall(arrQueries, count) {
  const sortRes = []

  return new Promise(resolve => {
    function handlePromise(prom, index) {
      return fetch(prom)
        .then(res => res.json())
        .then(data => {
          sortRes[index] = data
          if (sortRes.length === arrQueries.length) {
            resolve(sortRes)
            console.log('ok')
          }
        })
    }
    arrQueries.reduce((acc, prom, index) => {
      if (index < count) {
        return acc.then(handlePromise(prom, index))
      }
      return acc.then(() => handlePromise(prom, index))
    }, Promise.resolve())
  })
}
const g = [
  'https://jsonplaceholder.typicode.com/todos/1',
  'https://jsonplaceholder.typicode.com/todos/2',
  'https://jsonplaceholder.typicode.com/todos/3',
  'https://jsonplaceholder.typicode.com/todos/4',
  'https://jsonplaceholder.typicode.com/todos/5'
]
concurrentCall(g, 3).then(res => console.log(res))