- From: Jonas Sicking <jonas@sicking.cc>
- Date: Wed, 29 Feb 2012 15:26:13 +0100
- To: David Mandelin <dmandelin@mozilla.com>
- Cc: Jatinder Mann <jmann@microsoft.com>, Tony Gentilcore <tonyg@google.com>, public-web-perf@w3.org, James Robinson <jamesr@google.com>, Luke Wagner <lw@mozilla.com>
On Wed, Feb 29, 2012 at 1:26 AM, David Mandelin <dmandelin@mozilla.com> wrote: > [4.2] "A DOMHighResTimeStamp represents a number of milliseconds" > > Was milliseconds chosen for compatibility with other timing APIs? Seconds seems nicer conceptually but I understand if all the other related APIs are already ms. The two other spec that I can think of that use timing in a similar fashion is requestAnimationFrame and Navigation/Resource Timing. Both use milliseconds as unit so it makes sense to me to align with them for easier math. > [4.3] "On getting, the now attribute MUST return the number of milliseconds from the start of the navigation of the root document to the occurrence of the call to the now attribute." > > The main application of Performance.now seems to be relative timing, which doesn't particularly require any origin. It seems to me to be a bit easier to allow an arbitrary origin, so that the implementation doesn't have to track a zero time and subtract. Do some important applications require zero to be start of navigation? It might be interesting to align with requestAnimationFrame. It currently uses Jan 1st 1970 as 0 time though there's a note that that might change. See step 2 in http://dvcs.w3.org/hg/webperf/raw-file/tip/specs/RequestAnimationFrame/Overview.html#processingmodel I don't have a strong opinion either way though. / Jonas
Received on Wednesday, 29 February 2012 14:27:15 UTC