server/core/js/update.js

$(document).ready(function () {
	var updateEventSource = new OC.EventSource(OC.webroot+'/core/ajax/update.php');
	updateEventSource.listen('success', function(message) {
		$('<span>').append(message).append('<br />').appendTo($('.update'));
	});
	updateEventSource.listen('error', function(message) {
		$('<span>').addClass('error').append(message).append('<br />').appendTo($('.update'));
		message = 'Please reload the page.';
		$('<span>').addClass('error').append(message).append('<br />').appendTo($('.update'));
		updateEventSource.close();
	});
	updateEventSource.listen('failure', function(message) {
		$('<span>').addClass('error').append(message).append('<br />').appendTo($('.update'));
		$('<span>')
		.addClass('error bold')
		.append('<br />')
		.append(t('core', 'The update was unsuccessful. Please report this issue to the <a href="https://github.com/owncloud/core/issues" target="_blank">ownCloud community</a>.'))
		.appendTo($('.update'));
	});
	updateEventSource.listen('done', function(message) {
		$('<span>').addClass('bold').append('<br />').append(t('core', 'The update was successful. Redirecting you to ownCloud now.')).appendTo($('.update'));
		setTimeout(function () {
			window.location.href = OC.webroot;
		}, 3000);
	});
});