javascript - fetch retry request (on failure)

Question

I'm using browser's native fetch API for network requests. Also I am using the whatwg-fetch polyfill for unsupported browsers.

However I need to retry in case the request fails. Now there is this npm package whatwg-fetch-retry I found, but they haven't explained how to use it in their docs. Can somebody help me with this or suggest me an alternative?

Answer 1

From the fetch docs :

fetch('/users')
    .then(checkStatus)
    .then(parseJSON)
    .then(function(data) {
          console.log('succeeded', data)
    }).catch(function(error) {
          console.log('request failed', error)
    })

See that catch? Will trigger when fetch fails, you can fetch again there. Have a look at the Promise API.

Implementation example:

function wait(delay){
    return new Promise((resolve) => setTimeout(resolve, delay));
}

function fetchRetry(url, delay, tries, fetchOptions = {}) {
    function onError(err){
        triesLeft = tries - 1;
        if(!triesLeft){
            throw err;
        }
        return wait(delay).then(() => fetchRetry(url, delay, triesLeft, fetchOptions));
    }
    return fetch(url,fetchOptions).catch(onError);
}

Edit 1: as suggested by golopot, p-retry is a nice option.

Edit 2: simplified example code.