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.

npm package

npm install fetch-retry --save

Example

fetch-retry works the same way as fetch, but also accepts retries and retryDelay in the options argument. When omitted it will default to 3 retries with 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);
  });

Caveats

The fetch specification differs from jQuery.ajax() in mainly two ways that bear keeping in mind:

• The Promise returned from fetch() won't reject on HTTP error status even if the response is a HTTP 404 or 500. Instead, it will resolve normally, and it will only reject on network failure, or if anything prevented the request from completing.

Source: Github fetch