Functions XHR Request with Retries

xhr.js

export default (request) => { 
    const kvstore = require('kvstore');
    const xhr = require('xhr');
    const vault = require('vault'); // You can use the Vault to store a header/key for your backend 
                                    // to validate the request with, alternatively you can use IP whitelist
    
    
    const host = 'https://f8234c78.ngrok.io';
    var url = host + '/v1/webhooks/pubnub';
    
    // test 400
    url = "http://httpbin.org/status/400"
    
    // test 404
    //url = "http://httpbin.org/status/404"
    
    // test 500
    //url = "http://httpbin.org/status/500"
    
    const max_retries = 2; // XHR Limit is 3, PubNub can increase this by emailing support@pubnub.com
    const timeout = 5000; // 5 Second Timeout, Total Timeout can't be more than 10 seconds or Function auto-terminates
    
    const http_options = {
            'timeout': timeout,
            "method": "POST",
            "headers": {
                "API_KEY": "x",
                'Content-Type': 'application/json'
            },
            'body': request.message
    };


    function recursiveFetch(url, http_options, retries) {
        if (!retries) {
            retries = 0;
        }
        if (retries === max_retries) {

            throw new Error("Out of retries");
            return request.ok();
        }
        return xhr.fetch(url, http_options).then((resp) => {
            console.log(`XHR ${retries+1}: ${resp.status}`);
            if (resp.status != 200) {
                return recursiveFetch(url, http_options, ++retries);
            } else {
                return resp;
            }
        });
    }

    return vault.get("apiKey").then((apiKey) => {
            http_options.headers.API_KEY = apiKey;
            http_options.body.api_key = apiKey;
            
            console.log(request.message);
    
            return recursiveFetch(url, http_options);
    });
}