How is the "Fully Loaded" time measured?


From what I understand, time to “Document Complete” is measured when the onLoad event in the browser gets fired, correct? I’m curious about how the “Fully Loaded” time is calculated. Is there a similar browser event for this?


Correct - DocumentComplete = onLoad

Fully loaded waits for 2 seconds of no network activity (and no outstanding requests) after onLoad and then calls it done (only measures to the last activity, doesn’t include the 2 seconds of silence in the measurement).

That was quick, thanks!

“Fully loaded waits for 2 seconds of no network activity” – so its a specific measurement is it? I mean, the agents (in San Jose, Dulles, etc) monitor for outstanding requests after page load and then tell webpagetest servers that the page is “Fully Loaded”, correct?

Yes, it is specific to WebPagetest (well, technically to Pagetest which is the browser plugin that does all of the measuring).

As far as the actual mechanics go, the test agents don’t talk back to the server during testing. The server basically takes your test request, adds it to the queue for the given location and receives the test results when the agent finishes the testing. The test agents themselves launch the browser, capture all of the timings and measurements and then batch the results up to send back to the server. The “fully loaded” time is just one of the measurements that it sends back with the results. That is why you don’t get a whole lot of feedback about the progress of your test until the testing is actually done.