Guard against Webkit's extraneous calls to xhr.onreadystatechange #633
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
I would be more motivated to accept a workaround for am obscure WebKit issue if it was filed in their issue tracker. |
|
I've filed a bug with Chorme based on the info I have: http://code.google.com/p/chromium/issues/detail?id=159827 It references the Webkit reports I've found around the web. Good luck with your project. |
mislav
pushed a commit
that referenced
this pull request
Nov 13, 2012
The bug is present in Chrome 23.0.1271.64 and possibly iOS 6, and is reproducible using the debugger but otherwise occurs randomly. References #633 http://code.google.com/p/chromium/issues/detail?id=159827
|
OK, I think I just seen the issue in the wild while using GitHub.com: an ajax callback got executed twice in jQuery. Pulled your fix. Thanks! |
|
Great! Thanks a lot Mislav! |
lopper
pushed a commit
to buddydvd/zepto
that referenced
this pull request
Apr 24, 2013
The bug is present in Chrome 23.0.1271.64 and possibly iOS 6, and is reproducible using the debugger but otherwise occurs randomly. References madrobby#633 http://code.google.com/p/chromium/issues/detail?id=159827
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In certain cases Webkit will call the onreadystatechange method of a single XMLHttpRequest object multiple times indicating that it is ready (readyState == 4).
This results in Zepto's 'success' or 'error' methods being called multiple times for the same AJAX request.
This is documented in this thread:
http://stackoverflow.com/questions/12761255/can-xhr-trigger-onreadystatechange-multiple-times-with-readystate-done
with a jsfiddle here:
http://jsfiddle.net/44b3P/
and confirmed here:
http://osdir.com/ml/general/2012-10/msg12396.html
To reproduce in Zepto:
Expected: you should see 1 alert with the text 'error'
Actual: the alert with the text 'error' occurs 3 times
I'm working to find a way to reproduce this and submit upstream (at least to Chrome -- maybe to Webkit? -- We think it's a Webkit bug since we first observed this issue in Safari on iOS 6).
In the meantime this patch should resolve the issue in Zepto.
[1] While this is an awkward way to reproduce (clearly a debugger statement shouldn't be in production code) we've observed similar behavior in our production code where success functions are called multiple times for the same AJAX request -- usually when there's a lot going on on the page or the page hasn't completed loading.
The 'debugger' statement was the most reliable way I've seen to approximate these conditions and reproduce the behavior.