jmarantz commented on a change in pull request #1802: Prefer Paint Timing API
over chrome.loadTimes()
URL:
https://github.com/apache/incubator-pagespeed-mod/pull/1802#discussion_r225510986
##########
File path: net/instaweb/rewriter/add_instrumentation.js
##########
@@ -88,21 +88,30 @@ pagespeed.AddInstrumentation.prototype.sendBeacon =
function() {
timingApi['responseEnd'] - timingApi['responseStart']);
url += '&dom_c=' + (timingApi['domContentLoadedEventStart'] -
navStartTime);
- if (window['performance']['navigation']) {
- url += '&nt=' + window['performance']['navigation']['type'];
+ if (winPerf['navigation']) {
+ url += '&nt=' + winPerf['navigation']['type'];
}
var firstPaintTime = -1;
+ var paintEntries, loadTimes;
if (timingApi['msFirstPaint']) {
// IE.
firstPaintTime = timingApi['msFirstPaint'];
- } else if (window['chrome'] && window['chrome']['loadTimes']) {
+ } else if (winPerf['timeOrigin'] &&
+ winPerf['getEntriesByType'] &&
+ (paintEntries = winPerf['getEntriesByType']('paint')).length > 0) {
+ // Paint Timing API
+ // Note that getEntriesByType('paint') is sorted chronologically
+ firstPaintTime = Math.round(
+ winPerf['timeOrigin'] +
+ paintEntries[0]['startTime']);
+ } else if ((loadTimes = window['chrome']) && (loadTimes =
loadTimes['loadTimes'])) {
// Chrome. Note that window.chrome.loadTimes returns a time in seconds.
- firstPaintTime = Math.floor(
- window['chrome']['loadTimes']()['firstPaintTime'] * 1000);
+ firstPaintTime = Math.round(
+ loadTimes()['firstPaintTime'] * 1000);
}
- firstPaintTime = firstPaintTime - requestStartTime;
- if (firstPaintTime >= 0) {
- url += '&fp=' + firstPaintTime;
+ timeToFirstPaint = firstPaintTime - requestStartTime;
Review comment:
var
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