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Time to Interactive Measurement

JGannon
Guide

The Chrome browser is able to measure when a page is considered usable and can respond to user input (using blink user timing measurement). Lighthouse and Webpagetest (beta) (see details here (https://github.com/WPO-Foundation/webpagetest/blob/master/docs/Metrics/TimeToInteractive.md) are displaying this metric. It basically shows at what points after first meaningful paint the page is interactive or not in the timeline. This seems like a very important part of the user experience since it can show when the user is able to interact with the page. The problem becomes when the page is visually loaded to the user but they cannot interact with it due to JavaScript processing. Is this metric available in Dynatrace?

2 REPLIES 2

dominik_punz
Dynatrace Pro
Dynatrace Pro

Hi Joe,

the JS agent does not capture this Chrome-specific measurement but it captures all navigation timings, which also includes the DOM interactive metric. This should give you a similar timing.

Additionally wiht the upcoming AppMon 7 release we also introduced 2 new metrics that take rendering into account: Visually complete and Speed index. Here is a blog article that describes those 2 metrics:

https://www.dynatrace.com/blog/visually-complete-s...

Best regards,

Dominik

Hi Dominik - Thanks for the info. I'm not sure if the DOM Interactive metric would work since I need to find from first meaningful paint to calculate the metric. (Refer to https://github.com/WPO-Foundation/webpagetest/blob/master/docs/Metrics/TimeToInteractive.md). In looking at the Speed Index and Visually Complete timeline, there would need to be a calculation from the First Meaningful paint to "where there is a contiguous period of 5 seconds fully contained within the interactive window with no more than 2 in-flight requests" per the WPT documentation. This number becomes the Interactive time - the time at which the page is interactive. To me, simply showing the points at which the page is interactive versus non interactive would be useful enough and is used in the beta version of WPT on Chrome. However, since I haven't seen the latest version of Dynatrace with the Speed Index, etc, perhaps that metric will be captured for Chrome browsers?

FYI .. My understanding of the First Meaningful paint metric is that it is only available currently in Chrome.

In any event it seems like this metric combined with Speed Index would be powerful way to judge the complete user experience at 2 critical points - when the page is visible to the user so they can complete the task, and the point at which they are able to actuall interact with it.