[Webkit-unassigned] [Bug 67537] Implement a ProgressEvent constructor for JSC

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Tue Sep 6 21:18:51 PDT 2011


https://bugs.webkit.org/show_bug.cgi?id=67537





--- Comment #10 from Cameron McCormack <cam at mcc.id.au>  2011-09-06 21:18:50 PST ---
(In reply to comment #9)
> Cameron: Why do you think that 18446744073709551615 should be parsed as 18446744073709552000?
> 
> The ECMA-262 says that the ECMA Number should be the closest double value (Section 8.5: http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf). Therefore, toNumber(18446744073709551615) should be 18446744073709551616, since 18446744073709551616=2^64 can be exactly represented as a 64-bit double. In fact, JSValue::toNumber() converts 18446744073709551615 to 18446744073709551616.

Hmm, yes, you are correct.  2^64 is the closest number that can be represented exactly by a double.  So the resulting unsigned long long should indeed be 0.

> On the other hand, as you know, 18446744073709551615 is evaluated in JavaScript as 18446744073709552000 (e.g. alert(18446744073709551615)), but I do not know why this behavior is correct...

Is it the correct output from http://people.mozilla.org/~jorendorff/es5.html#sec-9.8.1?

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