RESOLVED FIXED 102848
REGRESSION(r131106): magnitude-perf.js calls bind on undefined 
https://bugs.webkit.org/show_bug.cgi?id=102848
Summary REGRESSION(r131106): magnitude-perf.js calls bind on undefined
Ryosuke Niwa
Reported 2012-11-20 16:12:27 PST
http://trac.webkit.org/changeset/131106/trunk/LayoutTests/resources/magnitude-perf.js replaced var nowFunction = window.performance.now || Date.now; with var nowFunction = window.performance.now.bind(window.performance) || Date.now; Calling bind on undefined object will results in an exception being thrown and "|| Date.now" is useless.
Attachments
Fixes the regression (1.36 KB, patch)
2012-11-20 16:13 PST, Ryosuke Niwa 		no flags
DetailsFormatted DiffDiff
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Ryosuke Niwa
Comment 1 2012-11-20 16:13:32 PST
Created attachment 175298 [details] Fixes the regression
Ojan Vafai
Comment 2 2012-11-20 16:34:11 PST
Comment on attachment 175298 [details] Fixes the regression I don't see why we need to call bind at all. Why can't this just be: var nowFunction = window.performance.now || Date.now; The original patch that added the bind call doesn't explain this.
James Simonsen
Comment 3 2012-11-20 16:50:58 PST
(In reply to comment #2) > (From update of attachment 175298 [details]) > I don't see why we need to call bind at all. Why can't this just be: > var nowFunction = window.performance.now || Date.now; > > The original patch that added the bind call doesn't explain this. You get a TypeError: Illegal invocation without it. You can test it in the console. Try storing now in a variable and then invoke that variable. I don't fully understand why. I think this answer might explain it: http://stackoverflow.com/questions/1007340/javascript-function-aliasing-doesnt-seem-to-work
Ojan Vafai
Comment 4 2012-11-20 16:52:44 PST
It seems wrong to me that you can alias Date.now but not window.performance.now.
James Simonsen
Comment 5 2012-11-20 16:59:01 PST
(In reply to comment #4) > It seems wrong to me that you can alias Date.now but not window.performance.now. performance.now() _does_ vary depending on which window you call it on. It measures the time since that window object started navigating.
Ojan Vafai
Comment 6 2012-11-20 17:01:40 PST
oic. Sad. I wonder if we can make aliasing of these things work. Probably not. :(
WebKit Review Bot
Comment 7 2012-11-20 17:11:44 PST
Comment on attachment 175298 [details] Fixes the regression Clearing flags on attachment: 175298 Committed r135335: <http://trac.webkit.org/changeset/135335>
WebKit Review Bot
Comment 8 2012-11-20 17:11:48 PST
All reviewed patches have been landed. Closing bug.
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