TaskQueue.js

import {EventEmitter} from "events"

export class TaskQueue extends EventEmitter {
    constructor(concurrency) {
        super()
        this.concurrency = concurrency
        this.running = 0
        this.queue = []
        
    }
    pushTask(task) {
        this.queue.push(task)
        process.nextTick(this.next.bind(this))
        return this
    }
    next() {
        if(this.queue.length===0&&this.running===0){
            this.emit("empty")
        }
        while (this.running < this.concurrency && this.queue.length) {
            const task = this.queue.shift()
           
            task((err) => {
                if(err){
                    this.emit("error",err)
                }

                this.running--
                process.nextTick(this.next.bind(this)) //EL FAKRA HANA
            })
            this.running++
        }
    }
}