Sunday, April 13, 2008

Firefox 3b5: the pain of using the bleeding edge

After seeing so many positive reviews of the upcoming Firefox 3, I decided to try the latest beta (5) version. It seems indeed to be fast when dealing with complex javascript. While there are a few features I am not too keen about [1], I liked the extra speed (and the reduced RAM usage) so much that I have been using it almost exclusively. That is until now, since I can't rely on it to test Crunchy. Update: this is no longer true, thanks to a reader's comment. The fix was to move the onblur event to the file input, indicated by HERE.

To load a local html file [2] into Crunchy, a two-step process has to be used due to normal javascript security:

<form name="browser_local"
onblur="document.submit_local.url.value =
<input name="filename" type="file" HERE >

<form action="/local" method="get" name="submit_local">
<input name="url" type="hidden">
<input class="crunchy" type="submit">
value="Load local html tutorial" />
The first form allows to browse the local drive for a particular file. The second one sends the chosen file's path to the browser as an argument to the "/local" action, something like /local?url=file_path. Unfortunately, when using Firefox 3 beta 5, no argument is passed and we get /local?url= instead. And of course no file can be loaded.

This file browser feature is not something I test regularly when working on Crunchy, nor is it something that can be tested via standard Python unit tests. [3] When I noticed the new bug, it never crossed my mind that this could be a "new Firefox feature" and thought it was something I had broken in Crunchy's code. [4] It was only after I tried a few old releases of Crunchy (to figure out when "I" broke the code) that I figured out that the problem was not due to anything I wrote.

I have not been able to find any note about this new behavior of Firefox. Since this is still a beta, I guess I'll have to wait until the final Firefox 3 release to figure out if I need to change the way I load files. [5]

[1] One change I don't like is the rather gaudy auto-suggest list when typing a url.

[2] The same method is used to load reStructuredText files and others.

[3] I really need to investigate twill for this.

[4] One more reason to have a complete unit test coverage. Since I don't, I automatically assumed it was something I had done.

[5] If anyone has any lead as to how to do so reliably in Firefox 3b5 as well as with other browsers, I'd be keen to hear about it.


illume said...

You should report a bug, and/or ask on their support channels.

Boris said...

Blur events don't bubble, per spec. The fact that they did for some types of form controls (but not others, note!) was a bug in Gecko 1.8.

You want to put the blur handler on the file input.

André said...

Thank you boris; this indeed solve the problem and I have updated the post accordingly.