pagePerformance.js

// perf stats
function getPerfStats() {
  var timing = window.performance.timing;
  var resourceList = window.performance.getEntriesByType("resource");
  var ajaxReq = [];
  for (i = 0; i < resourceList.length; i++) {
    if (resourceList[i].initiatorType == "xmlhttprequest") {
      ajaxReq.push({
        name: resourceList[i].name,
        time: resourceList[i].responseEnd - resourceList[i].startTime
      });

    }
  }

  var results = {
    ttfb: (timing.responseStart - timing.connectEnd) / 1000 + "s",
    domInteractive: (timing.domInteractive - timing.navigationStart) / 1000 + "s",
    domComplete: (timing.loadEventStart - timing.navigationStart) / 1000 + "s",
    loadEvent: (timing.loadEventEnd - timing.navigationStart) / 1000 + "s",
    ajax: ajaxReq
  };

  return results;

}


if (window.performance && window.performance.timing) {
  getPerfStats();
}