fetch-retry

What is fetch-retry?

The fetch-retry npm package is an extension of the native fetch API that adds the ability to automatically retry a failed HTTP request. This is particularly useful for dealing with transient network issues or temporary server-side errors. It allows developers to specify the number of retries, the retry delay, and other retry policies.

What are fetch-retry's main functionalities?

Automatic retries for failed requests

This feature allows fetch requests to be automatically retried a specified number of times with a delay between each attempt. The code sample shows how to wrap the native fetch with fetch-retry to make a GET request that retries up to 3 times with a 1-second delay between retries.

fetch = require('fetch-retry')(require('node-fetch'));

fetch('https://api.example.com', {
  retries: 3,
  retryDelay: 1000
}).then(function(response) {
  return response.json();
}).then(function(json) {
  console.log(json);
}).catch(function(error) {
  console.error(error);
});

Customizable retry on function

This feature allows developers to define a custom function to determine whether a request should be retried based on the attempt number, error, and response. The code sample demonstrates a custom retryOn function that retries the request if an error occurs or if the response status code is 500 or greater.

fetch = require('fetch-retry')(require('node-fetch'));

fetch('https://api.example.com', {
  retries: 4,
  retryDelay: 1000,
  retryOn: function(attempt, error, response) {
    if (error !== null || response.status >= 500) {
      return true;
    }
    return false;
  }
}).then(function(response) {
  return response.json();
}).then(function(json) {
  console.log(json);
}).catch(function(error) {
  console.error(error);
});

Other packages similar to fetch-retry

axios-retry

axios-retry is a package that provides similar retry functionality for Axios, a popular HTTP client. It allows for configuring retry conditions, delay strategies, and the number of retries. Unlike fetch-retry, which is built for the fetch API, axios-retry is specifically designed to work with Axios.

got

got is a more comprehensive HTTP request library that includes built-in retry functionality among many other features. It supports retries with a more extensive set of options and strategies compared to fetch-retry. Got is a standalone package, whereas fetch-retry is an extension of the native fetch API.

superagent-retry

superagent-retry extends the superagent library to add retry capabilities. It is similar to fetch-retry in that it adds retry functionality to an existing HTTP request library, but it is designed for superagent instead of fetch.

README

fetch-retry

Adds retry functionality to the Fetch API.

It wraps isomorphic-fetch and retries requests that fail due to network issues. It can also be configured to retry requests on specific HTTP status codes.

npm package

npm install fetch-retry --save

Example

fetch-retry is used the same way as fetch, but also accepts retries and retryDelay on the options object.

These properties are optional, and when omitted will default to 3 retries and a 1000ms retry delay.

var fetch = require('fetch-retry');

fetch(url, {
    retries: 3,
    retryDelay: 1000
  })
  .then(function(response) {
    return response.json();
  })
  .then(function(json) {
    // do something with the result
    console.log(json);
  });

Example: Retry on 503 (Service Unavailable)

The default behavior of fetch-retry is to only retry requests on network related issues, but it is also possible to configure it to retry on specific HTTP status codes. This is done by using the retryOn property, which expects an array of HTTP status codes.

fetch(url, {
    retryOn: [503]
  })
  .then(function(response) {
    return response.json();
  })
  .then(function(json) {
    // do something with the result
    console.log(json);
  });