Check if checkbox is NOT checked on click - jQuery

I want to check if a checkbox just got unchecked, when a user clicks on it. The reason for this is because i want to do a validation when a user unchecks a checkbox. Because atleast one checkbox needs to be checked. So if he unchecks the last one, then it automatically checks itself again.

With jQuery i can easily find out wether it's checked or not:

$('#check1').click(function() {
    if($(this).is(':checked'))
        alert('checked');
    else
        alert('unchecked');
});

But i actually only want to have an if statement that checks if a checkbox just got unchecked.

So i thought i could do that with the following code:

$('#check2').click(function() {
    if($(this).not(':checked'))
        alert('unchecked');
    else
        alert('checked');
});

But this will always show the 'unchecked' message. Not really what i was expecting...

demo: http://jsfiddle.net/tVM5H/

So eventually i need something like:

$('#check2').click(function() {
    if($(this).not(':checked')) {
        // Got unchecked, so something!!!
    }
});

But obviously this doesn't work. I rather don't want to use the first example, because then i'd have an unnecessary 'else' statement when i only need one 'if' statement.

So first thing, is this a jQuery bug? Cause to me it's unexpected behaviour. And second, anyone any ides for a good alternative?

Try this:

if(!$(this).is(':checked'))

demo

The answer already posted will work. If you want to use the jQuery :not you can do this:

if ($(this).is(':not(:checked)'))

or

if ($(this).attr('checked') == false)

jQuery to check for checked? Really?

if(!this.checked) {

Don't use a bazooka to do a razor's job.

$(document).ready(function() {
        $("#check1").click(function() {
            var checked = $(this).is(':checked');
            if (checked) {
                alert('checked');
            } else {
                alert('unchecked');
            }
        });
    });

<script type="text/javascript">

 if(jQuery('input[id=input_id]').is(':checked')){
  // Your Statment
 }else{
  // Your Statment
 }
 
 OR
 
 if(jQuery('input[name=input_name]').is(':checked')){
  // Your Statment
 }else{
  // Your Statment
 }

</script>

Code taken from here : http://chandreshrana.blogspot.in/2015/10/how-to-check-if-checkbox-is-checked-or.html

Check out some of the answers to this question - I think it might apply to yours:

https://stackoverflow.com/questions/11158874/how-to-run-click-function-after-default-behaviour-of-a-element/11159050#11159050

I think you're running into an inconsistency in the browser implementation of the onclick function. Some choose to toggle the checkbox before the event is fired and some after.

The Answer already posted .But We can use the jquery in this way also

demo

$(function(){
    $('#check1').click(function() {
        if($('#check1').attr('checked'))
            alert('checked');
        else
            alert('unchecked');
    });
    
    $('#check2').click(function() {
        if(!$('#check2').attr('checked'))
            alert('unchecked');
        else
            alert('checked');
    });
});

Do it like this

if (typeof $(this).attr("checked") == "undefined" )

// To check if checkbox is checked
if( $(this).attr("checked")=="checked")