#12061 closed bug (fixed)
$(window).beforeunload() clobbers previous handler and return values
Reported by: | dmethvin | Owned by: | |
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Priority: | low | Milestone: | 1.9 |
Component: | event | Version: | 1.7.2 |
Keywords: | Cc: | ||
Blocked by: | Blocking: |
Description
Moved from: http://bugs.jqueryui.com/ticket/8439
No matter what $(window).beforeunload(fn)
does, it cannot interact reliably with a mix of native inline functions. For other events, jQuery attaches a private native handler via addEventListener
or attachEvent
and manages jQuery handlers in its own data structures. Here we are all trying to share a single window.onbeforeunload
property, and it can't work.
Scenarios:
window.onbeforeunload = fn1; $(window).on("beforeunload", fn2); $(window).on("beforeunload", fn3);
Currently, we clobber fn1 and it is never called; only fn2 and fn3 would be called.
window.onbeforeunload = fn1; $(window).on("beforeunload", fn2); $(window).on("beforeunload", fn3); window.onbeforeunload = null;
If the code that sets fn1 later tries to remove it by null
ing out the handler, fn2 and fn3 don't run.
Having jQuery and the native code save any existing handler allows everyone to run, but prevents anyone from removing their handler; perhaps that is less of a problem in real-life scenarios.
There is also the return value problem. Unlike other event handlers that return false
as a flag, the onbeforeunload
event returns a string that is supposed to be displayed to the user, such as "Are you sure you want to leave this page? Your edits will be lost". In the case that there are multiple handlers what should be displayed to the user? Right now, we display the string from the *last* jQuery handler called.
Change History (11)
comment:1 Changed 11 years ago by
Component: | unfiled → event |
---|---|
Milestone: | None → 1.9 |
Priority: | undecided → low |
Status: | new → open |
comment:2 Changed 11 years ago by
comment:3 follow-up: 4 Changed 10 years ago by
Resolution: | → fixed |
---|---|
Status: | open → closed |
Fix #12061. Avoid window.onbeforeunload to permit multiple handlers. Close gh-894.
Changeset: 9dd0b010174dbfa70142a995a875a316337e1913
comment:4 Changed 10 years ago by
Replying to Oleg:
Changeset: 9dd0b010174dbfa70142a995a875a316337e1913
This does not appear to be the correct changeset link.
comment:5 Changed 10 years ago by
As of 1.9.2. release, existing onbeforeunload handler is still getting clobbered.
comment:6 Changed 10 years ago by
skarkkai, the test case above works. If you have a test case that fails can you post it?
comment:7 Changed 10 years ago by
Test case that also includes the native onbeforeunload, which also works.
comment:8 Changed 10 years ago by
The string to be showed has to be the last valid string so if the last callback returns null the page doesn't close without confirmation.
comment:10 Changed 10 years ago by
Hello
Recently I needed to make a queue that is updated via ajax.
It is updated recursively with a interval between each request.
Users complained that they were receiving an error message when accessed any link while the queue is updated.
So I needed to identify if the onError was called by a failure or because the user left navigation during the ajax request.
I fulfilled using the combination of $.ajaxError and $.bind('beforeunload', func) in the following code http://jsfiddle.net/7A6Ne/
But I just tested in Chrome 27, IE 10 and Firefox, so I'm afraid because I do not know if implementation of beforeunload is ok in all major browsers.
Should be fine if $.ajaxError tell us if user left navigation.
comment:11 Changed 10 years ago by
Sorry, I posted in the wrong ticket.
It is the correct http://bugs.jquery.com/ticket/13171
http://jsfiddle.net/fDccK/