polling function

polling.js

// XHR helper function
function xhrRequest(url, method) {
	return new Promise((resolve, reject) => {
		const req = new XMLHttpRequest();
		req.timeout = 6000;
		req.onload = () => {
			if (req.status === 200) {
				try {
					resolve(req.response);
				} catch (err) {
					reject(`Couldn't parse response. ${err.message}, ${req.response}`);
				}
			} else {
				reject(`Request had an error: ${req.status}`);
			}
		}
		req.ontimeout = () => {
			console.log("polling..")
			resolve(xhrRequest(url, method))
		}
		req.onerror = (err) => {
			console.log(err)
			reject(err)
		}
		req.open(method, url, true);
		req.responseType = 'json';
		req.send();
	});
}