How to check whether a checkbox is checked in jQue

Question

I need to check the checked property of a checkbox and perform an action based on the checked property using jQuery.

For example, if the age checkbox is checked, then I need to show a textbox to enter age, else hide the textbox.

But the following code returns false by default:

if ($('#isAgeSelected').attr('checked'))
{
    $("#txtAge").show();
}
else
{
    $("#txtAge").hide();
}

How do I successfully query the checked property?

Answer 1

Use this:

if ($('input[name="salary_in.Basic"]:checked').length > 0)

The length is greater than zero if the checkbox is checked.

Answer 2

I ran in to the exact same issue. I have an ASP.NET checkbox

<asp:CheckBox ID="chkBox1" CssClass='cssChkBox1' runat="server" />

In the jQuery code I used the following selector to check if the checkbox was checked or not, and it seems to work like a charm.

if ($("'.cssChkBox1 input[type=checkbox]'").is(':checked'))
{ ... } else { ... }

I'm sure you can also use the ID instead of the CssClass,

if ($("'#cssChkBox1 input[type=checkbox]'").is(':checked'))
{ ... } else { ... }

I hope this helps you.

Answer 3

I decided to post an answer on how to do that exact same thing without jQuery. Just because I'm a rebel.

var ageCheckbox = document.getElementById('isAgeSelected');
var ageInput = document.getElementById('txtAge');

// Just because of IE <333
ageCheckbox.onchange = function() {
    // Check if the checkbox is checked, and show/hide the text field.
    ageInput.hidden = this.checked ? false : true;
};

First you get both elements by their ID. Then you assign the checkboxe's onchange event a function that checks whether the checkbox got checked and sets the hidden property of the age text field appropriately. In that example using the ternary operator.

Here is a fiddle for you to test it.

Addendum

If cross-browser compatibility is an issue then I propose to set the CSS display property to none and inline.

elem.style.display = this.checked ? 'inline' : 'none';

Slower but cross-browser compatible.

Answer 4

Using the Click event handler for the checkbox property is unreliable, as the checked property can change during the execution of the event handler itself!

Ideally, you'd want to put your code into a change event handler such as it is fired every time the value of the check box is changed (independent of how it's done so).

$('#isAgeSelected').bind('change', function () {

   if ($(this).is(':checked'))
     $("#txtAge").show();
   else
     $("#txtAge").hide();
});

Answer 5

Using jQuery > 1.6

<input type="checkbox" value="1" name="checkMeOut" id="checkMeOut" checked="checked" />

// traditional attr
$('#checkMeOut').attr('checked'); // "checked"
// new property method
$('#checkMeOut').prop('checked'); // true

Using the new property method:

if($('#checkMeOut').prop('checked')) {
    // something when checked
} else {
    // something else when not
}

Answer 6

I believe you could do this:

if ($('#isAgeSelected :checked').size() > 0)
{
    $("#txtAge").show(); 
} else { 
    $("#txtAge").hide();
}