document.oncontextmenu=new function("event.returnvalue=false");  
    document.onselectstart=new function("event.returnvalue=false"); 


    //防f12
     document.oncontextmenu = function () { return false; };
        document.onkeydown = function () {
            if (window.event && window.event.keycode == 123) {
                event.keycode = 0;
                event.returnvalue = false;
                return false;
            }
        }; 


        //防ctrl+s
        window.addeventlistener('keydown', function (e) {
            if(e.keycode == 83 && (navigator.platform.match('mac') ? e.metakey : e.ctrlkey)){
                e.preventdefault();
            }
        })



        //防ctrl+u
        var arr = [123, 17, 18];
        document.oncontextmenu = new function("event.returnvalue=false;"),//禁用右键

        window.onkeydown = function (e) {
            var keycode = e.keycode || e.which || e.charcode;
            var ctrlkey = e.ctrlkey || e.metakey;
            console.log(keycode + "--" + keycode);
            if (ctrlkey && keycode == 85) {
                console.log("ctrl+u");
                e.preventdefault();
            }
            if (arr.indexof(keycode) > -1) {
                console.log("other");
                e.preventdefault();
            }
            //e.preventdefault();
            //return false;
        }