// disable right click
    document.addEventListener('contextmenu', event => event.preventDefault());

    document.onkeydown = function (e) {

        // disable F12 key
        if(e.keyCode == 123) {
            return false;
        }

        // disable I key
        if(e.ctrlKey && e.shiftKey && e.keyCode == 73){
            return false;
        }

        // disable J key
        if(e.ctrlKey && e.shiftKey && e.keyCode == 74) {
            return false;
        }

        // disable U key
        if(e.ctrlKey && e.keyCode == 85) {
            return false;
        }
    }