disable f12 key javascript

 use this code to head tag


<script language="JavaScript">

//////////F12 disable code////////////////////////
    document.onkeypress = function (event) {
        event = (event || window.event);
        if (event.keyCode == 123) {
           //alert('No F-12');
            return false;
        }
    }
    document.onmousedown = function (event) {
        event = (event || window.event);
        if (event.keyCode == 123) {
            //alert('No F-keys');
            return false;
        }
    }
document.onkeydown = function (event) {
        event = (event || window.event);
        if (event.keyCode == 123) {
            //alert('No F-keys');
            return false;
        }
    }
/////////////////////end///////////////////////
</script>

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