measure load times in real user browsers.
Real user performance trackers often can track dom ready and dom load, if you want more detail on the load time of individual resources you have to make individual tests on a controlled environment. This is because browser don't expose an Javascript API to monitor network activity (unless a plugin is installed, not practical for real user monitoring).
PageStopwatch estimates load time of resources (scripts, images and css) on real user browsers, by detecting when script, img or link tags are added to the document. This can be acheived used MutationObserver, which is present in most modern browsers:
- Chrome 26+
- Firefox 14+
- Safari 6+
Basically the requirement is MutationObserver support, you can test it by checking pageStopwatch.supported
// start and show load times on console
var stopwatch = pageStopwatch.start().notifyConsole();
// send to google analytics (using _trackTiming)
stopwatch.notifyGA();
// later...
setTimeout(function(){
// render a waterfall chart in the page
stopwatch.drawAt(document.getElementById('#pageLoadChart'));
}, 15000);The MIT License (MIT)
Copyright (c) 2013 Benjamin Eidelman
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