The promise-retry npm package allows users to retry a promise-returning or an async function until it resolves or reaches a maximum number of attempts. It is useful for handling operations that may temporarily fail due to external factors such as network issues or service unavailability.

What are promise-retry's main functionalities?

Basic retry functionality

This feature allows you to retry a promise until it either resolves or fails a specified number of times. The `retry` function is passed to the promise-returning function, and it can be called to retry the operation.

const promiseRetry = require('promise-retry');

function myFunction() {
  return new Promise((resolve, reject) => {
    // An operation that may fail
  });
}

promiseRetry(function (retry, number) {
  console.log('attempt number', number);

  return myFunction().catch(retry);
})
.then(function (value) {
  // resolved value
})
.catch(function (error) {
  // operation failed
});

Custom retry options

This feature allows you to specify custom options for retries, such as the maximum number of attempts, the factor by which the timeout increases, and the minimum and maximum timeout between retries.

const promiseRetry = require('promise-retry');

promiseRetry(function (retry, number) {
  // Your promise-returning function
}, {
  retries: 5, // Maximum number of attempts
  factor: 2, // The exponential factor
  minTimeout: 1 * 1000, // The number of milliseconds before starting the first retry
  maxTimeout: 60 * 1000 // The maximum number of milliseconds between two retries
})
.then(function (value) {
  // resolved value
})
.catch(function (error) {
  // operation failed
});

Other packages similar to promise-retry

Readme

Source

node-promise-retry

Retries a function that returns a promise, leveraging the power of the retry module to the promises world.

There's already some modules that are able to retry functions that return promises but they were rather difficult to use or do not offer an easy to do conditional retries.

Installation

$ npm install promise-retry

Usage

promiseRetry(fn, [options])

Calls fn until the returned promise ends up fulfilled or rejected with an error different than a retry error.
The options argument is an object which maps to the retry module options:

retries: The maximum amount of times to retry the operation. Default is 10.
factor: The exponential factor to use. Default is 2.
minTimeout: The number of milliseconds before starting the first retry. Default is 1000.
maxTimeout: The maximum number of milliseconds between two retries. Default is Infinity.
randomize: Randomizes the timeouts by multiplying with a factor between 1 to 2. Default is false.

The fn function will receive a retry function as its first argument that should be called with an error whenever you want to retry fn. The retry function will always throw an error.
If there's retries left, it will throw a special retry error that will be handled internally to call fn again. If there's no retries left, it will throw the actual error passed to it.

var promiseRetry = require('promise-retry');

// Simple example
promiseRetry(function (retry, number) {
    console.log('attempt number', number);

    return doSomething()
    .catch(retry);
})
.then(function (value) {
    // ..
}, function (err) {
    // ..
});

// Conditional example
promiseRetry(function (retry, number) {
    console.log('attempt number', number);

    return doSomething()
    .catch(function (err) {
        if (err.code === 'ETIMEDOUT') {
            retry(err);
        }

        throw err;
    });
})
.then(function (value) {
    // ..
}, function (err) {
    // ..
});

Tests

$ npm test

License

Released under the MIT License.

Keywords

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Last updated on 11 Jan 2015

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