Closed Bug 510234 Opened 15 years ago Closed 14 years ago

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


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




Tracking Status
status1.9.2 --- beta4-fixed


(Reporter: kangax, Assigned: mayhemer)




(Keywords: html5, testcase)


(2 files)

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

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

It also supports `clear()` method, which as per current "Web Storage" specs draft (

"... 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`: = 'bar';
'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
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
Component: General → DOM: Mozilla Extensions
Ever confirmed: true
Keywords: html5, testcase
Product: Firefox → Core
QA Contact: general → general
Version: unspecified → Trunk
Assignee: nobody → honzab.moz
Flags: blocking1.9.2?
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"
I think we should block on this web compatibility bug for 1.9.2.
Flags: blocking1.9.2? → blocking1.9.2+
OS: Mac OS X → All
Priority: -- → P2
Hardware: x86 → All
Target Milestone: --- → mozilla1.9.2
Attachment #409678 - Flags: review?(jst)
Comment on attachment 409678 [details] [diff] [review]
v1 [Checkin comment 6]

Attachment #409678 - Flags: superreview+
Attachment #409678 - Flags: review?(jst)
Attachment #409678 - Flags: review+
Comment on attachment 409678 [details] [diff] [review]
v1 [Checkin comment 6]
Attachment #409678 - Attachment description: v1 → v1 [Checkin comment 6]
Attachment #409678 - Flags: approval1.9.2?
Closed: 14 years ago
Resolution: --- → FIXED
Comment on attachment 409678 [details] [diff] [review]
v1 [Checkin comment 6]

(this is a blocker, doesn't need explicit approval, please land ASAP)
Attachment #409678 - Flags: approval1.9.2?
Component: DOM: Mozilla Extensions → DOM
Component: DOM → DOM: Core & HTML
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