需求

• 控制网络请求并发数
• 控制并发按顺序返回结果

---

码

/**
* 控制并发
* @param {Function} fn 逻辑处理函数
* @param {Array} arr 发送的数据
* @param {Number} [max=3] 并发数 默认3
* @param {Number} [order=false] 按顺序返回执行结果 默认false
* @param {Number} [retry=1] 重试次数 默认1
* @returns {Promise} 返回Promise
*/
const reqPool = (fn, arr, max = 3, order = false, retry = 1) => {let reqList        = [...arr],                                        //不改变arrresData        = order ? Array(reqList.length).fill(0, 0) : [],   //  order = true 填充返回的数据curRuningCount = 0,                                               //限制内的第n个并发 runedCount     = 0,                                               //已执行的数量                         runingIndex    = 0;                                               //当前执行下标                       return new Promise(res => {const run = _ => {while (curRuningCount < max && reqList.length) {curRuningCount++const chunk = reqList.shift();(i => {/*** 当前重试次数 */let _retry = 0const add = (i2, data) => fn(data).then(r => {runedCount++order ? resData[i2] = r : resData.push(r)}).catch(err => {_retry++const repMore = _retry > retryif (!repMore) {add(i2, data)console.log(data, '重试' + _retry + '次');} else {order ? resData[i2] = err : resData.push(err)runedCount++}}).finally(_ => {curRuningCount--if (runedCount === arr.length) res(resData)run()});add(i, chunk)})(runingIndex++)}}run()})
}// 请求配置 | 请求体
const chunks = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];/**
* 逻辑处理函数 | 如：发起请求
* @param {Object} chunk
* @returns {Promise} 
*/
const req = chunk => new Promise((res, rej) => setTimeout(_ => Math.random() > .8 ? rej('失败----' + chunk) : res('结果' + chunk), Math.random() * 100 + 100))reqPool(req, chunks, 3, true).then(res => console.log(res))

运行图