Answer by Aamir Shahzad for Check if checkbox is checked with jQuery

You can do it simply like;

Working Fiddle

HTML

<input id="checkbox" type="checkbox" />

jQuery

$(document).ready(function () {
    var ckbox = $('#checkbox');

    $('input').on('click',function () {
        if (ckbox.is(':checked')) {
            alert('You have Checked it');
        } else {
            alert('You Un-Checked it');
        }
    });
});

or even simpler;

$("#checkbox").attr("checked") ? alert("Checked") : alert("Unchecked");

If the checkbox is checked it will return true otherwise undefined