Bug 27922 – Strict equality of MimeType host objects is not respected

• Status: NEW
• Component: WebCore JavaScript

[Tobie Langel]

Strict equality of Host objects of [[Class]] MimeType isn't respected (not that it's mandated by any specs).

To reproduce:

    window.navigator.mimeTypes[0] === window.navigator.mimeTypes[0];
    // returns false (expected true).


Given that:
      
    var mt = window.navigator.mimeTypes[0];
    mt === mt; // returns true (as expected);

I suspect that new wrappers are created each time the property is accessed.

Platforms affected:
  Safari Version 4.0.1 (5530.18) on Mac 10.5.7
  Webkit nightly Version 4.0.1 (5530.18), r46646 Mac OS 10.5.7
  haven't tried elsewhere.

[Sam Weinig]

Yeah, this is quite unfortunate.  We create a new MimeType for every invocation of the item method.

PassRefPtr<MimeType> MimeTypeArray::item(unsigned index)
{
    PluginData* data = getPluginData();
    if (!data)
        return 0;
    const Vector<MimeClassInfo*>& mimes = data->mimes();
    if (index >= mimes.size())
        return 0;
    return MimeType::create(data, index).get();
}

[Nikita Vasilyev]

Furthermore, navigator.mimeTypes[0] == navigator.mimeTypes[0] // true

Also, navigator.mimeTypes[0] == navigator.mimeTypes[0].enabledPlugin[0] == navigator.mimeTypes[0].enabledPlugin[0].enabledPlugin[0] // should be true, but false

I'm trying to serialize whole window object to a string, but I've a problems with navigator.mimeTypes due to circular references and broken '=='.

[Nikita Vasilyev]

(In reply to comment #2)
> Furthermore, navigator.mimeTypes[0] == navigator.mimeTypes[0] // true

Whoops. I mean false!