refactor: added requestStart to the TTFB formula #9
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Super excited to see Time to First Byte joining the WebVitals family 🌲🚀🌕
I was wondering why TTFB is based only as
navigationEntry.responseStart
instead of being the combination ofnavigationEntry.responseStart - navigationEntry.requestStart
. Doing this subtraction will imply not including browser set up, redirects, or tcp and ssl negotiation in the final result.I originally learn about this way of calculating TTFB by the Assessing Loading Performance in Real Life with Navigation and Resource Timing article.
I made a tiny PR with this change in case you and the team believe
navigationEntry.responseStart - navigationEntry.requestStart
could work better to guide developer with this tool.Thank you @philipwalton 🙌