Userscript template

template.user.js

// ==UserScript==
// @name            Script name
// @description     Description
// @namespace       https://yourwebsite.com
// @version         0.1.0
// @author          Your name
// @license         MIT
// @released        2016-10-18
// @updated         2016-10-18
// @match           *://example.com/*
// @match           *://www.example.com/*
// @run-at          document-start
// ==/UserScript==
(() => {
	'use strict';

	// before the DOM has loaded
	
	document.addEventListener('DOMContentLoaded', e => {
		// after the DOM has loaded
		
		// silently fails in Firefox if placed outside when `document-start`
		GM_addStyle('body { background: hotPink }');
	});
})();