zulip-desktop/app/renderer/js/main.js

window.onload = function getURL() {
	const request = require('request');
	const JsonDB = require('node-json-db');
	const ipcRenderer = require('electron').ipcRenderer;
	const dialogs = require('dialogs')();

	const db = new JsonDB('domain', true, true);
	const data = db.getData('/');

	if (data.domain) {
		window.location.href = data.domain;
	} else {
		dialogs.prompt('Enter the URL for your Zulip server', url => {
			const newurl = 'https://' + url.replace(/^https?:\/\//, '');
			const checkURL = newurl + '/static/audio/zulip.ogg';

			request(checkURL, (error, response) => {
				if (!error && response.statusCode !== 404) {
					db.push('/domain', newurl);
					ipcRenderer.send('new-domain', newurl);
					window.location.href = newurl;
				} else {
					dialogs.alert('Not valid url');
					console.log('Not valid url');
				}
			});
		});
	}

	const getInput = document.getElementsByTagName('input')[0];

	getInput.setAttribute('placeholder', 'zulip.example.com'); // add placeholder
	getInput.setAttribute('spellcheck', 'false'); // no spellcheck for form
};