checkbox is always "on"

Question

Hy!

When Uploadify send the file to the action, I need to know if the checbox is checked or not, so I did:

    $('#uploaded').uploadify({
        'uploader': '/uploadify.swf',
        'cancelImg': '/cancel.png',
        'script': '/Interaction/Upload',
        'multi': true,
        'auto': false,
        'method': 'post',
        'scriptData': {'Checkbox': $('#checkbox').val()},
    });

But I aways get an "on" value. No matter if is checked or not.

can anyone help? Tks.

UPDATE:

I realized that uploadify is getting the checkbox when the page is loaded.This means that if I change the checkbox (or any other type of input) the uploadify will get the initial value, in this case, "checkbox = false".

How can I send a form with uploadify?

Tks.

score 64 · Answer 1 · answered Jul 06 '11 at 19:56

64

try $('#checkbox').is(':checked')

answered Jul 06 '11 at 19:56

MikeM

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4

I'm getting always "false" using this to. – Thiago Jul 06 '11 at 20:27

Gopi Reddy · Answer 2 · 2012-07-02T22:14:48.337

A checkbox's value is always 'on'. The HTML Form sends the value to the server only if the checkbox is checked. If the box is not checked, then the request parameter will be absent. This semantics is apparently to minimize the differences between checkboxes and radio buttons.

The HTML Form implements the following semantics:

if ($('#mycheckbox').is(':checked')) {
    payload['mycheckbox'] = $('#mycheckbox').val();
}

You can either mimic this semantics in Ajax or send the 'checked' flag directly as follows:

payload['mycheckbox'] = $('#mycheckbox').is(':checked');

I'd recommend mimic'ing the HTML Form semantics. Irrespective of what the client does, I'd recommend the following in the server code:

if mycheckbox param exists and its value is either 'true' or 'on' {  // pseudo code of course
    // mycheckbox is checked
} else {
    // mycheckbox is unchecked
}

Hope this explanation helps.

The on semantics are very confusing... I hope it made someone's life easier! Even a disabled checkbox has a value of "on"... — Derek Litz, Sep 05 '13 at 23:01
Very confusing implementation - but this answer helped me understand why val() always returns 'on' for checkboxes. — Daniel Howard, Mar 01 '14 at 18:00

score 18 · Answer 3 · answered Jun 23 '13 at 21:47

18

There is a pretty handy way to check all these element properties like disabled, checked, etc. with the prop function. This also converts it to boolean:

$('#checkbox').prop('checked'); // -> true/false
$('#checkbox').prop('disabled'); // -> true/false

answered Jun 23 '13 at 21:47

Gabriel Petrovay

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wtf @chx101! what do you want from me? :P :D – Gabriel Petrovay Apr 21 '15 at 16:13
Vanilla JS: var isChecked = elDom.checked // _> true/false – n1ru4l Oct 25 '16 at 08:00

score 10 · Answer 4 · answered Jul 06 '11 at 19:58

10

Try this

$('#checkbox').is(':checked')

answered Jul 06 '11 at 19:58

ShankarSangoli

67,648
11
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I like how this method gives you a boolean. – kd7iwp Feb 20 '12 at 19:41

score 7 · Answer 5 · answered Jul 06 '11 at 19:56

7

Change:

$('#checkbox').val()

to

$('#checkbox').attr('checked')

answered Jul 06 '11 at 19:56

rossipedia

47,308
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1

I'm getting always "false". I don't know why. – Thiago Jul 06 '11 at 20:22

score 1 · Answer 6 · answered May 09 '12 at 12:51

1

I just had the same problem and found this solution:

if($("input[name='yourcheckbox']").is(':checked')) {
   console.log('chb checked');
} else {
   console.log('chb not checked');
}

answered May 09 '12 at 12:51

nimrod

5,408
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score 0 · Answer 7 · answered Jul 06 '11 at 19:57

0

Use:

$('#checkbox').attr('checked')

answered Jul 06 '11 at 19:57

Mark Pope

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score 0 · Answer 8 · answered May 10 '21 at 18:32

0

var checkboxValue = $('#id').prop('checked');

answered May 10 '21 at 18:32

Lahiru Pradeep Ariyasinghe

51
1

score -1 · Answer 9 · answered Mar 16 '12 at 13:06

-1

You can give

if(jQuery(this).attr('checked')){ // u have to use this selector according to your function it may be .click .live or else..

Thanks

answered Mar 16 '12 at 13:06

Javascript Coder

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checkbox is always "on"

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