fetchretry.js

//rewrite from https://github.com/jonbern/fetch-retry
let fetchretry = (url, options) => {
    var retries = (options && options.retries) ? options.retries : 3;
    var retryDelay = (options && options.retryDelay) ? options.retryDelay : 500;
    return new Promise((resolve, reject) => {
        let wrappedFetch = n => fetch(url, options).then(response => resolve(response)).catch(error => n > 0 ? setTimeout(() => wrappedFetch(--n), retryDelay) : reject(error));
        wrappedFetch(retries);
    });
};