510234 - `localStorage.clear()` doesn't actually delete its properties

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect, P2)

Description

[Juriy "kangax" Zaytsev]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2
Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2

`localStorage` supports short accessor notation (as an alternative to `getItem`/`setItem`): 

localStorage.foo = 'bar';
localStorage.foo; // 'bar'

It also supports `clear()` method, which as per current "Web Storage" specs draft (http://www.w3.org/TR/webstorage/):

"... must atomically cause the list associated with the object to be emptied of all key/value pairs, if there are any. If there are none, then the method must do nothing."

What looks like a bug is that even after `clear()`, keys are still "present" in `localStorage`:

localStorage.foo = 'bar';
localStorage.clear();
'foo' in localStorage; // true

Is this an expected behavior? 

Note that the last statement returns `false` in at least WebKit and IE8 (and allows to check for presence of a value without resorting to a more verbose - `getItem(key) !== null`).

Thank you.

Reproducible: Always

Comment 1

[Nickolay_Ponomarev]

The spec also says "The names of the supported named properties on a Storage  object are the keys of each key/value pair currently present in the list associated with the object.", so this looks like a bug.

See the URL field for testcase.

Confirmed in Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.3a1pre) Gecko/20090919 Minefield/3.7a1pre

Comment 2

[Honza Bambas (:mayhemer)]

From jst on IRC: "I think that'd be a matter of finding the XPConnect wrapper for the localStorage object when calling clear, and calling JS_ClearScope() on its JSObject"

Comment 3

[Johnny Stenback (:jst)]

I think we should block on this web compatibility bug for 1.9.2.

Comment 4

[Honza Bambas (:mayhemer)]

Attachment: v1 [Checkin comment 6]

Comment 5

[Johnny Stenback (:jst)]

Comment on attachment 409678 [details] [diff] [review]
v1 [Checkin comment 6]

r+sr=jst

Comment 6

[Honza Bambas (:mayhemer)]

Comment on attachment 409678 [details] [diff] [review]
v1 [Checkin comment 6]

http://hg.mozilla.org/mozilla-central/rev/5df9f71b9e98

Comment 7

[Mike Beltzner [:beltzner, not reading bugmail]]

Comment on attachment 409678 [details] [diff] [review]
v1 [Checkin comment 6]

(this is a blocker, doesn't need explicit approval, please land ASAP)

Comment 8

[Honza Bambas (:mayhemer)]

Attachment: as landed on 1.9.2 [Checking comment 8]

http://hg.mozilla.org/releases/mozilla-1.9.2/rev/247cda75bc87