Re: About window.performance namespace

   Greetings!

   Yes, those determined enough would still be able to swap out the timing
object. It's not ideal but rather some
compromise to avoid breaking existing codes using the window.performance
object. Though, it still makes sense
to me to have underneath attributes read-only as they are properties of the
page/navigation.

   It will be great if you can join us at this week's conf call to chat more
on this.

cheers,
Zhiheng

On Tue, Dec 21, 2010 at 12:22 AM, Sigbjørn Vik <sigbjorn@opera.com> wrote:

> On Tue, 21 Dec 2010 01:11:41 +0100, Zhiheng Wang <zhihengw@google.com>
> wrote:
>
>  On the other hand, I see valid use cases for overwriting the sub-objects.
>>> For instance in my debug environment, I know one of the attributes is way
>>> off, so I want to change/overwrite that, in order to see the correct
>>> output
>>> from the third party timing script.
>>>
>>>
>>    Instead of changing/overwriting individual attributes, you can create a
>> mock performance object and swap out window.performance in the debugging
>> environment.
>> It takes some extra work but testing/debugging probably worth it. :-)
>>
>
> But in this case, the attributes on the performance object are trivially
> replaceable:
>
> var perf2 = window.performance;
> perf2.timing = new Object();
> window.performance = perf2;[1]
>
> If this can be done this easily, I am not certain I see the benefit of
> making window.performance.timing read-only in the first place?
>
> [1]
> Or a more roundabout way, in the case the read-only attribute would be
> copied across on the first line above:
> var perf2 = new Object();
> for (attr in window.performance) {
>        if (attr != "timing") perf2[attr] = window.performance[attr];
> }
> perf2.timing = new Object();
> window.performance = perf2;
>
>
> --
> Sigbjørn Vik
> Quality Assurance
> Opera Software
>
>