926369 - Object.keys method returns different results when using on global window object

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[duongna]

User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.69 Safari/537.36

Steps to reproduce:

Run the following script:
<script>
    console.log(Object.keys(window));
    if(top == window){}
    console.log(Object.keys(window));
</script>


Actual results:

Returned value of the 2 calls are different:
["window", "document", "InstallTrigger", "console", "process", "global", "Mocha", "mocha", "sinon", "expect", "location", "mouseEvents", "msPointerEvents", "keyEvents", "uiEvents", "bubbleEvents", "touchEvents", "gestureEvents", "before", "after", "beforeEach", "afterEach", "context", "describe", "xcontext", "xdescribe", "specify", "it", "xspecify", "xit", "getInterface"]
["window", "document", "InstallTrigger", "console", "process", "global", "Mocha", "mocha", "sinon", "expect", "location", "mouseEvents", "msPointerEvents", "keyEvents", "uiEvents", "bubbleEvents", "touchEvents", "gestureEvents", "before", "after", "beforeEach", "afterEach", "context", "describe", "xcontext", "xdescribe", "specify", "it", "xspecify", "xit", "getInterface", "top"]


Expected results:

They should definitely be the same

Comment 1

[David Teller [:Yoric] - still alive but not very active]

Unless I'm mistaken, this is the expected behavior, per specifications of JS/DOM:
  |if (top == window) {}|
implicitly declares global value |top|, i.e. |window.top|.

Am I missing something?

Comment 2

[duongna]

I thought that |top| is a built in property of the |window| and should be available from beginning. Is it lazy loaded in Firefox?

Comment 3

[Jeff Walden [:Waldo]]

top is an unforgeable property, so it should exist directly on |window|.  That it doesn't, initially, is probably a side effect of window not being WebIDL yet.  This is a DOM bug, really, not a JS bug.

Comment 4

[David Bruant]

(In reply to Jeff Walden [:Waldo] (remove +bmo to email) from comment #3)
> top is an unforgeable property, so it should exist directly on |window|. 
> That it doesn't, initially, is probably a side effect of window not being
> WebIDL yet.  This is a DOM bug, really, not a JS bug.
yes. @duongna, this bug should be fixed as a side-effect of fixing of bug 789261.
There are other ways in which using the window object doesn't comply to ECMAScript reflection methods. That should all be fixed when bug 789261 is fixed.

Comment 5

[Boris Zbarsky [:bzbarsky]]

This was fixed by bug 918345.