auth.html

<script>
token = "";
function init() {
	var url = window.location.href;
	var subdomain = readUrlParam(url, 'subdomain');
	console.log(subdomain);
	if (url.indexOf('https://talk.premiumplus.io/auth.html') !== -1) {
		if (url.indexOf('access_token=') !== -1) {
			var access_token = readUrlParam(url, 'access_token');
			token = access_token;
			localStorage.setItem('zauth', access_token);
			localStorage.setItem('zdomain', subdomain);
			window.location.hash = "";
			console.log(access_token+"auth001");
			window.opener.postMessage(access_token, "https://talk.premiumplus.io/index.html");

		}
		if (url.indexOf('error=') !== -1) {
			var error_desc = readUrlParam(url, 'error_description');
			var msg = 'Authorization error: ' + error_desc;
			showError(msg);
		}
	}
	if (localStorage.getItem('zauth')) {
		var access_token = localStorage.getItem('zauth');
		token = access_token;
		console.log(access_token+"auth002");
		window.opener.postMessage(access_token, "https://talk.premiumplus.io/index.html");
	} else {
		console.log("auth003");
		startAuthFlow(subdomain);
	}
}

function startAuthFlow(subdomain) {
	var endpoint = 'https://' + subdomain + '.zendesk.com/oauth/authorizations/new';
	var url_params = '?' +
	'response_type=token' + '&' +
	'redirect_uri=https://talk.premiumplus.io/auth.html' + '&' +
	'client_id=talk_status' + '&' +
	'scope=' + encodeURIComponent('read write');
	window.location.href = endpoint + url_params;
}

function readUrlParam(url, param) {
	param += '=';
	if (url.indexOf(param) !== -1) {
		var start = url.indexOf(param) + param.length;
		var value = url.substr(start);
		if (value.indexOf('&') !== -1) {
			var end = value.indexOf('&');
			value = value.substring(0, end);
		}
		return value;
	} else {
		return false;
	}
}

window.addEventListener('load', init, false);
</script>