A utility for easily repeating a promise-based task, until it succeeds. Works both in Node and in the browser.

Installation

$ npm install repeat-promise-until-resolved

Table of Contents

• Examples
  • Usage
  • Basic example
  • Additional configuration
• API

Examples

Usage

In a node-based environment:

const repeatPromiseUntilResolved = require('repeat-promise-until-resolved');   

If you're using it in the browser, without any build system, simply expose it to the global object:

 <script src="node_modules/repeat-promise-until-resolved/index.js"></script>
 

Basic example

const repeatPromiseUntilResolved = require('repeat-promise-until-resolved');
const axios = require('axios');

(async()=>{

    //Create a function that returns a promise, which you want to repeat until resolved. If you're not familiar with async functions, note that they return a promise.
    async function promiseFactory() {    
        const { data } = await axios('https://jsonplaceholder.typicode.com/todos/1')
        console.log(data)        
    }

    try {
        //Pass the promise-producing function, and an optional config object. The default maxAttempts value is 3.        
        await repeatPromiseUntilResolved(promiseFactory, { maxAttempts: 3});//Will be performed 3 times at most, until it finally fails.
    } catch (error) {//An error will be thrown, only after the final failing attempt.        
        console.log('final fail',error)
    } 
})()

  

Additional configuration

  (async()=>{
    async function promiseFactory() {
 
        const { data } = await axios('https://jsonplaceholder.typicode.com/todos/1')
        console.log('success',data)
    }

    //Hook into each attempt, and receive the attempt number
    const onAttempt = (attempt) => {
        console.log(attempt);
    }

    //Hook into every error thrown, and receive the Error object and the attempt number.
    const onError = (error, attempt) => {      
        console.log(error.message, attempt);
    }

    try {
        //Limit to 5 attempts, and create a delay of 2 seconds between each attempt. timeout: Wait up to 5 seconds for each promise to resolve, until it's manually rejected(and retried)
        //Also pass functions to the hooks.
        await repeatPromiseUntilResolved(promiseFactory, { maxAttempts: 5, delay: 2000, timeout:5000, onAttempt, onError });
    } catch (error) {        
        console.log('final fail',error)
    } 
})()

API

function repeatPromiseUntilResolved(promiseFactory,config):Promise

| Parameter | type | Description | | ----------- |---- | ------------------------------------------------------------ | | promiseFactory | function | A function that returns the promise you want to "repeat" | | config | object| A configuration and hook object. Not required| | config.maxAttempts | number| Number of maximum attempts(including the first one) | | config.delay | number| Number of milliseconds to wait between each retry. Useful in network requests | | config.timeout | number| Number of milliseconds to wait, until the promise is manually rejected. Default is 8000 | | config.onAttempt | function| Hook into each attempt. Receives the number of the current attempt as an argument | | config.onError | function| Hook into each failed attempt. Receives the Error object as an argument | | config.shouldStop | function| Hook into each failed attempt. Receives the Error object as an argument. Return true, if you want the repetition to stop |