Navigation Performance API

Trying to make sense of this API. And possibly figure out if its possible to use it with XHR objects. Attempt: #1.

HTML

<script src="https://raw.github.com/gist/1586738/3fbe15131982504dd292aaefc37705841c518abe/log.js"></script>
<ul class="a"></ul>

JavaScript

var times = function(timing) {
    var properties = Object.getOwnPropertyNames(timing),
        start = timing.navigationStart,
        property, index, length = properties.length,
        time,
        duration;

    // rebase timing from navigationStart so we can actually read the values
    for (index = 0; index < length; index++) {
        property = properties[index];
        time = parseInt(timing[property], 10);
        duration = time > 0 ? time - start : time;
        
        // let's make it less verbose for now
        if (duration > 0) {
            log(property, duration);
$(".a").append("<li>" + property + duration + "</li>") 
        }
    }
};

$(function() {
    times(window.performance.timing);
});