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Negative TTFB on Firefox

See original GitHub issue

I’m seeing instances of negative values of getTTFB(), exclusively on Firefox, despite the docs claiming that Firefox is a supported browser.

Seems related to this issue.

If it helps, I found that these Navigation Timing attributes are also negative in these cases.

connect_end
connect_start
domain_lookup_start
fetch_start
redirect_end
redirect_start
request_start
response_end
response_start
secure_connection_start
time_to_first_byte

Issue Analytics

State:
Created 2 years ago
Reactions:2
Comments:7 (4 by maintainers)

Top GitHub Comments

4reactions

philipwaltoncommented, May 4, 2021

Filed: https://bugzilla.mozilla.org/show_bug.cgi?id=1709427

1reaction

bradfrostycommented, May 5, 2021

@nicjansma wrote a great blog post about Navigation Timing in Practice several years back. It might be a bit out of date, but there’s some useful context in there including a list of browser bugs (at the time) such as responseStart being reported prior to navigationStart (Ctrl-F for “Browser Bugs”).

+1 for adding to the library. His suggestion was:

If you’re analyzing NavigationTiming data, you should ensure that all timestamps increment according to the timeline. If not, you should probably question all of the timestamps and discard.