805794 - Moz-prefixed features can be shadowed by 'var' declarations.

Status: RESOLVED DUPLICATE of bug 770844

(Firefox :: General, defect)

Description

[cscott]

Standard fields of the window object are not shadowed by local variable definitions:

// this works fine
var navigator = window.navigator;

But other fields (formerly prefixed features, it seems) get improperly shadowed:

// this sets both indexedDB *and* window.indexedDB to 'undefined'!
var indexedDB = window.indexedDB;
// ditto (if your browser still has prefixed indexedDB)
var mozIndexedDB = window.mozIndexedDB;

Test case at: http://mozbugs.github.cscott.net/shadow/
Occurs on nightly Firefox/Android as well.

Comment 1

[cscott]

I've also filed a chrome bug: http://code.google.com/p/chromium/issues/detail?id=158049

Chrome does fine with webkitIndexedDB, but has shadowing problems with requestAnimationFrame.

Comment 2

[Boris Zbarsky [:bzbarsky]]

This will happen for any property that lives on the proto chain of the global; see discussion in bug 770844.

The only reason it works for navigator is that navigator is an own property of the window in Gecko at the moment for various hacky reasons.