Latest editor draft: https://w3c.github.io/hr-time/ HR-Time-3 introduced this attribute, which is useful for developers to be able to compare timings of entries sourced from different time origins (like windows or workers). It has already been implemented in Firefox, Edge has it in Preview, and will also be shipped by Chrome[1]. [1] https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/ck9M6Ev21lo
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