Last-child feature detection

Created by @laustdeleuran Tested and discussed with @emilchristensen Core method inspired by @westonruter

by laustdeleuran

HTML

<script src="http://dev.ljd.dk/resources/modernizr-2.0.6-c1.js"></script>
<div id="results"></div>
<ul id="credits" style="margin-top:1em; font-size:80%;">
    <li>By <a href="http://ljd.dk">Laust Deleuran</a> - <a href="http://twitter.com/laustdeleuran">@laustdeleuran</a></li>
    <li>Tested and discussed with <a href="http://twitter.com/emilchristensen">@emilchristensen</a></li>
    <li>Core method inspired by <a href="http://jsfiddle.net/westonruter/eAVp2/">Weston Ruter</a></li>
</ul>

JavaScript

// :last-child pseudo selector test.
// By @laustdeleuran and @emilchristensen
// Please see http://reference.sitepoint.com/css/pseudoclass-lastchild for weird :last-child behaviour in FireFox below 2.0 and Safari below 2.0.
// Original Modernizr test here: http://jsfiddle.net/laustdeleuran/3rEVe/ and Pure JS here: http://jsfiddle.net/laustdeleuran/hvZ3J/
Modernizr.addTest('lastchild', function () {
    return Modernizr.testStyles("#modernizr div {width:100px} #modernizr :last-child{width:200px;display:block}", function(elem) {
        return elem.lastChild.offsetWidth > elem.firstChild.offsetWidth;
    }, 1);
});

// Output result
document.getElementById("results").innerHTML = Modernizr.lastchild ? "Yes! I support the :last-child pseudo selector." : "No - so sorry, but I have no clue what the :last-child pseudo selector is.";
document.getElementById("results").style.color = Modernizr.lastchild ? "green" : "red";