GreaseMonkey script to change Timestamps in github to the user's timezone and locale settings

github-relative-dates-timezone.js.user.js

// ==UserScript==
// @name        github-relative-dates-timezone.js
// @namespace   http://danny-edel.de/
// @include     https://github.com/*
// @version     2
// ==/UserScript==


/** Walk through all <time> Tags and
 * use toLocaleString() to render them to a
 * user-friendly format.
 */
function updateGithubTimestamps() {
	var githubTimes = document.getElementsByClassName('js-relative-date');
	for(var i=0; i<githubTimes.length; i++) {
		var time = githubTimes[i];

		// parse the time from the 'datetime' attribute
		var datetimeStringOld = time.getAttribute('datetime');

		// dateSeconds: seconds since 1970-01-01 00:00:00 zulu
		var dateSeconds = Date.parse(datetimeStringOld);

		// build a date object with the (timezone-agnostic) timepoint
		var date = new Date(dateSeconds);

		// format the date according to locale's rules
		var localString = date.toLocaleString();

		// write it to the 'title' attribute (gets shown upon mouseover)
		time.setAttribute('title', localString);
	}
}

var timerVar = setInterval( function(){ updateGithubTimestamps() }, 5000);