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Bug in FAQs for checkboxes

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Bug in FAQs for checkboxes

by Greg Glockner :: Rate this Message:

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Hi, after some painful debugging, I determined that there is a bug in
the jQuery FAQs about how to clear a checkbox.  Specifically, if you
have a strict XHTML document, you *cannot* use .attr("checked","") to
clear a checkbox. Instead, you must use .removeAttr("checked").  See
the following PHP code sample:


<?
        header('Content-type: application/xhtml+xml');
        print '<?xml version="1.0" encoding="iso-8859-1"?>' . "\n";
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Checkbox test</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/
libs/jquery/1.3/jquery.min.js"></script>
</head>
<body>
<p>
<input type="checkbox" id="c"/> I'll be checked/unchecked.
<input type="button" value="Check" onclick='$("#c").attr
("checked","checked")'/>
<input type="button" value="Uncheck - fail" onclick='$("#c").attr
("checked","")'/>
<input type="button" value="Uncheck - good" onclick='$("#c").removeAttr
("checked")'/>
</p>
</body>
</html>


I have updated the FAQ accordingly. Hope this helps.

Re: Bug in FAQs for checkboxes

by Greg Glockner :: Rate this Message:

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Hi, it's worse than I originally thought. Put my sample code on a PHP
server, and load the page from a browser. Using removeAttr does,
indeed, remove the checked attribute and unchecks the box.  Next,
click on the box to select it, then press the button marked Uncheck -
good. This time, jQuery does NOT uncheck the box.  This is a bug.

I've been digging into the source code for jQuery 1.2.6 and 1.3.1, and
here's what I've observed.  First, jQuery 1.3.1 detects the page as
XML (XHTML), while jQuery 1.2.6 does not.  (If you simply put my code
in a file without sending the headers, then jQuery does not detect the
page as XML).  With 1.2.6, jQuery.attr sets notxml to true (saying
it's not XML) while 1.3.1 sets notxml to false (saying the page is
XML).  From here, I get a bit lost inside the jQuery source code, but
what I could determine is that the code marked "If applicable, access
the attribute via the DOM 0 way" is able to modify the checked
property, while the alternate code (when notxml is false) is unable to
modify the checked property.

I've got a workaround - to set the DOM checked property directly to
true/false, but I thought someone should research this issue.

Thanks, Greg Glockner.


On Jan 24, 8:24 pm, Greg Glockner <greg.glock...@...> wrote:

> Hi, after some painful debugging, I determined that there is a bug in
> the jQuery FAQs about how to clear a checkbox.  Specifically, if you
> have a strict XHTML document, you *cannot* use .attr("checked","") to
> clear a checkbox. Instead, you must use .removeAttr("checked").  See
> the following PHP code sample:
>
> <?
>         header('Content-type: application/xhtml+xml');
>         print '<?xml version="1.0" encoding="iso-8859-1"?>' . "\n";
> ?>
> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
>       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
> <html xmlns="http://www.w3.org/1999/xhtml">
> <head>
> <title>Checkbox test</title>
> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/
> libs/jquery/1.3/jquery.min.js"></script>
> </head>
> <body>
> <p>
> <input type="checkbox" id="c"/> I'll be checked/unchecked.
> <input type="button" value="Check" onclick='$("#c").attr
> ("checked","checked")'/>
> <input type="button" value="Uncheck - fail" onclick='$("#c").attr
> ("checked","")'/>
> <input type="button" value="Uncheck - good" onclick='$("#c").removeAttr
> ("checked")'/>
> </p>
> </body>
> </html>
>
> I have updated the FAQ accordingly. Hope this helps.

Re: Bug in FAQs for checkboxes

by Karl Swedberg-2 :: Rate this Message:

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Hi Greg, 

Since this sounds like it could be a bug in the jQuery source code, not just in the FAQs, would you mind posting what you've discovered to the jquery-dev list (http://groups.google.com/group/jquery-dev)? It'll probably get more attention there, and someone may suggest that you file a bug report if they're able to confirm the problem.

Thanks so much,

--Karl

____________
Karl Swedberg

On Jan 25, 2009, at 2:21 AM, Greg Glockner wrote:


Hi, it's worse than I originally thought. Put my sample code on a PHP
server, and load the page from a browser. Using removeAttr does,
indeed, remove the checked attribute and unchecks the box.  Next,
click on the box to select it, then press the button marked Uncheck -
good. This time, jQuery does NOT uncheck the box.  This is a bug.

I've been digging into the source code for jQuery 1.2.6 and 1.3.1, and
here's what I've observed.  First, jQuery 1.3.1 detects the page as
XML (XHTML), while jQuery 1.2.6 does not.  (If you simply put my code
in a file without sending the headers, then jQuery does not detect the
page as XML).  With 1.2.6, jQuery.attr sets notxml to true (saying
it's not XML) while 1.3.1 sets notxml to false (saying the page is
XML).  From here, I get a bit lost inside the jQuery source code, but
what I could determine is that the code marked "If applicable, access
the attribute via the DOM 0 way" is able to modify the checked
property, while the alternate code (when notxml is false) is unable to
modify the checked property.

I've got a workaround - to set the DOM checked property directly to
true/false, but I thought someone should research this issue.

Thanks, Greg Glockner.


On Jan 24, 8:24 pm, Greg Glockner <greg.glock...@...> wrote:
Hi, after some painful debugging, I determined that there is a bug in
the jQuery FAQs about how to clear a checkbox.  Specifically, if you
have a strict XHTML document, you *cannot* use .attr("checked","") to
clear a checkbox. Instead, you must use .removeAttr("checked").  See
the following PHP code sample:

<?
        header('Content-type: application/xhtml+xml');
        print '<?xml version="1.0" encoding="iso-8859-1"?>' . "\n";
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Checkbox test</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/
libs/jquery/1.3/jquery.min.js"></script>
</head>
<body>
<p>
<input type="checkbox" id="c"/> I'll be checked/unchecked.
<input type="button" value="Check" onclick='$("#c").attr
("checked","checked")'/>
<input type="button" value="Uncheck - fail" onclick='$("#c").attr
("checked","")'/>
<input type="button" value="Uncheck - good" onclick='$("#c").removeAttr
("checked")'/>
</p>
</body>
</html>

I have updated the FAQ accordingly. Hope this helps.

Re: Bug in FAQs for checkboxes

by Karl Swedberg-2 :: Rate this Message:

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Ack! Sorry, Greg. After replying to you I checked the jquery-dev moderation queue and, lo and behold, you had already posted there. I've promoted you to member of the jquery-dev list, so your emails shouldn't get stuck in moderation from here on out.

cheers,

--Karl

On Jan 25, 2009, at 2:38 PM, Karl Swedberg wrote:

Hi Greg, 

Since this sounds like it could be a bug in the jQuery source code, not just in the FAQs, would you mind posting what you've discovered to the jquery-dev list (http://groups.google.com/group/jquery-dev)? It'll probably get more attention there, and someone may suggest that you file a bug report if they're able to confirm the problem.

Thanks so much,

--Karl

____________
Karl Swedberg

On Jan 25, 2009, at 2:21 AM, Greg Glockner wrote:


Hi, it's worse than I originally thought. Put my sample code on a PHP
server, and load the page from a browser. Using removeAttr does,
indeed, remove the checked attribute and unchecks the box.  Next,
click on the box to select it, then press the button marked Uncheck -
good. This time, jQuery does NOT uncheck the box.  This is a bug.

I've been digging into the source code for jQuery 1.2.6 and 1.3.1, and
here's what I've observed.  First, jQuery 1.3.1 detects the page as
XML (XHTML), while jQuery 1.2.6 does not.  (If you simply put my code
in a file without sending the headers, then jQuery does not detect the
page as XML).  With 1.2.6, jQuery.attr sets notxml to true (saying
it's not XML) while 1.3.1 sets notxml to false (saying the page is
XML).  From here, I get a bit lost inside the jQuery source code, but
what I could determine is that the code marked "If applicable, access
the attribute via the DOM 0 way" is able to modify the checked
property, while the alternate code (when notxml is false) is unable to
modify the checked property.

I've got a workaround - to set the DOM checked property directly to
true/false, but I thought someone should research this issue.

Thanks, Greg Glockner.


On Jan 24, 8:24 pm, Greg Glockner <greg.glock...@...> wrote:
Hi, after some painful debugging, I determined that there is a bug in
the jQuery FAQs about how to clear a checkbox.  Specifically, if you
have a strict XHTML document, you *cannot* use .attr("checked","") to
clear a checkbox. Instead, you must use .removeAttr("checked").  See
the following PHP code sample:

<?
        header('Content-type: application/xhtml+xml');
        print '<?xml version="1.0" encoding="iso-8859-1"?>' . "\n";
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Checkbox test</title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/
libs/jquery/1.3/jquery.min.js"></script>
</head>
<body>
<p>
<input type="checkbox" id="c"/> I'll be checked/unchecked.
<input type="button" value="Check" onclick='$("#c").attr
("checked","checked")'/>
<input type="button" value="Uncheck - fail" onclick='$("#c").attr
("checked","")'/>
<input type="button" value="Uncheck - good" onclick='$("#c").removeAttr
("checked")'/>
</p>
</body>
</html>

I have updated the FAQ accordingly. Hope this helps.
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