Enqueu

Promise queue for concurrency control

Installation

$ npm i enqueu

or

<script src="https://unpkg.com/[email protected]/dist/index.js"></script>

Example

In this case you will get "hey, my name is yoann, how are you ?, bye" and without Enqueu "my name is yoann, bye, how are you ?, hey".

import Enqueu from "enqueu";

const queu = new Enqueu();

queu
  .add(() => new Promise((r) => setTimeout(r, 3000)))
  .then((_) => console.log("hey"));

queu
  .add(() => new Promise((r) => setTimeout(r, 2000)))
  .then((_) => console.log("how are you ?"));

queu
  .add(() => new Promise((r) => setTimeout(r, 1000)))
  .then((_) => console.log("bye"));

queu
  .add(() => new Promise((r) => setTimeout(r, 500)), { priority: 1 }) //from 1 to Infinity
  .then((_) => console.log("my name is Yoann"));

With event listener

For example in this case if you click 4 times at once on the button you will get "10, 5, 2.5". But without Enqueu you will get "1.25, 1.25, 1.25, 1.25".

const queu = new Enqueu({ maxSize: 3 }); //the maximum size of the queu is 3 (other will be throwed off)

let count = 20;

document.querySelector("button").addEventListener(
  "click",
  queu.createFn(function () {
    count = count / 2;
    return new Promise((r) =>
      setTimeout(function () {
        r(count);
      }, count * 1000)
    );
  })
);

Enqueu

Constructor

• maxSize Max size of the queu
• maxConcurrency Max promise as the same time

Attibutes

• isPaused Return a boolean to see if the queu is paused or not
• pending Return the number of pending functions
• queu Return the queu

Methods

• add(fn: Function, options: Options = {}): Function Add the function to the queu
• createFn(fn: Function, options: Options = {}): Function Create a function that will add "fn" to the queu on call (useful for addEventListener for example)
• pause() Pause the queu
• start() Start the queu after a pause
• onEmpty(fn: Function) Call the function passed as argument when the queu is empty
• onQueuElementExecuted(fn: Function) Call the function passed as argument when the a new queu function is started
• onQueuElementFinishExecution(fn: Function) Call the function passed as argument when the a new queu function which started is finished
• clear() Clear the queu
• remove(fn: Function) Remove a function from the queu
• removeFromIndex(index: number) Remove a specified indexed element in the queu