Check and Uncheck Checkbox using JQuery

<input type="checkbox" name="checkboxname" value="checkboxvalue" />

<input type="button" onclick="show_checked()" value="Show" />

<input type="button" onclick="Change_checked(true)" value="On" />

<input type="button" onclick="Change_checked(false)" value="Off" />

<script type="text/javascript">

    function show_checked() {

        alert($('input[name=foo]').is(':checked'));

        //alert($('input[name=foo]').attr('checked'));

    }

    function Change_checked(checkvalue) {

        if (checkvalue) {
           //use \" before and after checkboxname for avoid slash(/) inside the name

            $('input[name =\"checkboxname\"]').attr("checked", checkvalue)

        }

        else {

            $('input[name = \"checkboxname\" ]').attr("checked", false)

            $('input[name = \"checkboxname\" ]').removeAttr("checked")

        }

    }

    

</script>