Have questions about images on the web? Tweet your questions to @ChromiumDev with #AskChrome and we'll answer the top questions in our next #AskChrome episode on YouTube.

User Timing Marks and Measures

Overview

The User Timing API enables you to measure your app's JavaScript performance. The basic idea is that you decide which parts of your scripts you want to optimize, and then you instrument those parts of your scripts with the User Timing API. From there, you can access the results from JavaScript using the API, or view them on your Chrome DevTools Timeline Recordings.

Recommendations

This audit is not structured as a "pass" or "fail" test. It's just an opportunity to discover a useful API that can aid you in measuring your app's performance. The score that Lighthouse reports for this audit corresponds to the number of User Timing Marks and Measures that it finds in your app.

When your app does include User Timing Marks and Measures, you'll see these Marks and Measures in your Lighthouse report.

Check out User Timing API for an introduction on using the User Timing API to measure your app's JavaScript performance.

More information

Lighthouse extracts User Timing data from Chrome's Trace Event Profiling Tool.

Feedback

Was this page helpful?
Yes
What was the best thing about this page?
It helped me complete my goal(s)
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
It had the information I needed
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
It had accurate information
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
It was easy to read
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
Something else
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
No
What was the worst thing about this page?
It didn't help me complete my goal(s)
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
It was missing information I needed
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
It had inaccurate information
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
It was hard to read
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.
Something else
Thank you for the feedback. If you have specific ideas on how to improve this page, please create an issue.