How to catch check/uncheck event of <input type="checkbox" /> with jQuery?

Question

The title should be clear

Answer 1

use the click event for best compatibility with MSIE

$(document).ready(function() {
    $("input[type=checkbox]").click(function() {
        alert("state changed");
    });
});

Answer 2

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

$("#something").click( function(){
   if( $(this).is(':checked') ) alert("checked");
});

Answer 3

Use the :checked selector to determine the checkbox's state:

$('input[type=checkbox]').click(function() {
    if($(this).is(':checked')) {
        ...
    } else {
        ...
    }
});