How to use Navigation Timing API with Google Analytics

navigationTiming-analytics.js

function getPerfStats() {
  var timing = window.performance.timing;
  return {
    dns: timing.domainLookupEnd - timing.domainLookupStart,
    connect: timing.connectEnd - timing.connectStart,
    ttfb: timing.responseStart - timing.connectEnd,
    basePage: timing.responseEnd - timing.responseStart,
    frontEnd: timing.loadEventStart - timing.responseEnd
  };
}

window.onload = function() {
  if (window.performance && window.performance.timing) {
    var ntStats = getPerfStats();
    //_trackEvent(category, action, opt_label, opt_value, opt_noninteraction)
    _gaq.push(["_trackEvent", "Navigation Timing", "DNS", undefined, ntStats.dns, true]);
    _gaq.push(["_trackEvent", "Navigation Timing", "Connect", undefined, ntStats.connect, true]);
    _gaq.push(["_trackEvent", "Navigation Timing", "TTFB", undefined, ntStats.ttfb, true]);
    _gaq.push(["_trackEvent", "Navigation Timing", "BasePage", undefined, ntStats.basePage, true]);
    _gaq.push(["_trackEvent", "Navigation Timing", "FrontEnd", undefined, ntStats.frontEnd, true]);
  }
};