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Re: About window.performance namespace

From: Jonas Sicking <jonas@sicking.cc>
Date: Wed, 5 Jan 2011 00:19:23 -0800
Message-ID: <AANLkTi=4nmOEePStaS3o8Ljzc7DB_Zjhm3cviQCqg8Py@mail.gmail.com>
To: Zhiheng Wang <zhihengw@google.com>
Cc: Sigbjørn Vik <sigbjorn@opera.com>, public-web-perf <public-web-perf@w3.org>
Note that just making it replaceable doesn't help code like:

if (!performance) {
  ... lazy-initialization code here ...
}
codeUsingPerformance();

or

if (...someTests...) {
  performance = true;
}

... much later ...
if (performance) {

}

I haven't really followed the discussions here, but is there a reason
the property couldn't be named something with a smaller risk of
collisions, such as "pagePerformance" or "performanceMetrics"?

/ Jonas

On Tue, Jan 4, 2011 at 11:56 PM, Zhiheng Wang <zhihengw@google.com> wrote:
>    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
>>
>
>
Received on Wednesday, 5 January 2011 08:21:07 UTC

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