Below code snippet explains how HTML input checkbox checked unchecked event can be handled using jQuery
<input type = "checkbox" id = "chk" checked = "checked" />
<input type = "text" id = "txt" />
<script type = "text/javascript" src = ""></script>
<script type="text/javascript">
    $("#chk").live("click", function () {
        if ($("#chk").is(":checked")) {
            $("#txt").attr("disabled", "");
        } else {
            $("#txt").attr("disabled", "disabled");
In the above example the checkbox with Id “chk” has been assigned a click event handler using jQuery live function.
Inside the function it checks whether the checkbox is checked or not using the :checked property of jQuery and enables or disables the HTML input textbox.