实现
通过Promise.allSettled+递归的方法，在请求队列不为空时，不断的请求。
代码
//模拟Promise请求
function request(url, time = 1) {
return new Promise((resolve, reject) => {
setTimeout(() => {
console.log('请求结束：'+url);
if(Math.random() > 0.5){
resolve('成功')
}else{
reject('错误;')
}
}, time * 1e3)
})
}
//通过类来控制并发数
class PromiseController {
constructor(requestList,maxRequestNum) {
//请求数组
this.requestList = requestList
//最大并发数
this.maxRequestNum = Math.min(maxRequestNum, requestList.length)
//储存结果
this.responseList = []
//请求池
this.requestPool = []
}
addPool() {
const list = this.requestList.splice(this.maxRequestNum)
//返回promise并添加到请求池中
this.requestPool = this.requestList.map(el => {
return el()
})
this.requestList = list
}
//递归执行，跑完后返回结果
async run() {
if(!this.isFinish()) {
this.addPool()
try {
const res = await Promise.allSettled(this.requestPool)
this.responseList.push(...res)
return await this.run()
}catch(err) {
console.log('err',err)
}
}else {
return this.responseList
}
}
isFinish() {
return this.requestList.length <= 0 && this.requestPool.length <= 0
}
}
const requests = [() => request('1'),
() => request('2'),
() => request('3'),
() => request('4')]
const pc = new PromiseController(requests,3)
pc.run().then(res => {
console.log('response',res)
})
