fix(web-vitals): Fix TTFB capture in Safari #3106
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kamilogorek
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Dec 8, 2020
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Safari doesn't support
performance.timeOriginhttps://developer.mozilla.org/en-US/docs/Web/API/Performance/timeOriginThis regression was introduced in #3019
As a result, this caused TTFB captures to be
nullwhen normalized with respect totransaction.startTime:When using the timeOrigin polyfill (i.e.
browserPerformanceTimeOrigin), the numbers propagate properly. Unfortunately, this may cause normalized TTFB values to be negative.We simply take its absolute value:
In addition, I've updated the
getTTFB()implementation to the latest web-vitals revision: https://github.com/GoogleChrome/web-vitals/blob/eef03ad99882b6cdb6e35eee4c2d9b220152ed0a/src/getTTFB.ts