Check if a check box is checked or not (js/jquery)

Question

I want to check if a certain check box is selected using JavaScript/jQuery.

Here is the code I tried:

var a; if ($("#add_desc").checked == 1){ a = "true"; }else{ a= "false"; }

I have also tried:

var a; if ($("#add_desc").checked){ a= "true"; }else{ a= "false"; }

It always returns false once I alert the variable a.

Any idea why it won't work for me? Am I doing it wrong?

Thanks!

By way of explanation: $('#add_desc') returns a jQuery object that contains the element, rather than the element itself, so doesn't have a checked property. Adding the [0] returns the first element contained in the jQuery object (your actual checkbox), which does have a checked property. — Anthony Grist
– Anthony Grist, Commented Apr 20, 2012 at 21:07
You can also access those properties with jQuery 1.6's .prop(). api.jquery.com/prop — CWSpear
– CWSpear, Commented Apr 20, 2012 at 21:08
@CameronSpear You can, though to be honest this entire example is trivial enough that there's no need to use jQuery at all. — Anthony Grist
– Anthony Grist, Commented Apr 20, 2012 at 21:09
@AnthonyGrist I've noticed you need to index jquery's id selector too. Why does it not say this in the jQuery manual? They do it like the OP is doing it.. — Nick Rolando
– Nick Rolando, Commented Apr 20, 2012 at 21:09

user400654 · Accepted Answer · 2012-04-20 21:08:02Z

To get the value of the checked property on a checkbox input, use the .prop() method, or get the value directly from the DOM element. [0] returns the first selected DOM element.

var a; if ($("#add_desc")[0].checked){ a= "true"; }else{ a= "false"; }

or

var a; if ($("#add_desc").prop("checked")){ a= "true"; }else{ a= "false"; }

Edit
For versions of jQuery older than 1.6, .prop didn't exist, use .attr as a direct replacement.

Robin Maben · Accepted Answer · 2012-04-20 21:09:44Z

6

Simple,

var a = $('#element:checkbox').is(':checked');

answered Apr 20, 2012 at 21:09

Robin Maben

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2 Comments

Mike B Over a year ago

That would make the variable a boolean while in his example he's assigning string values...

Robin Maben Over a year ago

Yes. But how hard would it be to do a toString() if required?

Nathan · Accepted Answer · 2012-04-20 21:13:36Z

The "jQuery way" would be to use .is(":checked"):

var a; if ($("#add_desc").is(":checked")){ // box is checked a = "true"; } else{ // box is not checked a= "false"; }

I use this a lot in my web apps and it works perfectly.

From the jQuery .is documentation page:

Unlike other filtering methods, .is() does not create a new jQuery object. Instead, it allows you to test the contents of a jQuery object without modification. This is often useful inside callbacks, such as event handlers.

Mike B · Accepted Answer · 2012-08-06 22:52:12Z

The ternary operator in javascript combined with jQuery .is() is the shortest solution.

var a = ($("#add_desc").is(":checked")) ? "true" : "false";

newtron · Accepted Answer · 2012-04-20 21:06:42Z

try:

if ($('#add_desc').is(':checked')) { a = "true"; } else { b = "false"; }

you may also not want to use strings, i.e. use true and false instead of "true" and "false"

Shehzad · Accepted Answer · 2012-04-20 21:18:37Z

2

Try

$get("#add_desc").checked == true

Also

$("#add_desc").prop("checked", true); $("#add_desc").prop("checked", false);

edited Apr 20, 2012 at 21:18

answered Apr 20, 2012 at 21:07

Shehzad

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1 Comment

Nathan Over a year ago

Note that .prop() did not exist prior to jQuery 1.6. Use .attr() for any earlier versions of jQuery.

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