网页全屏和屏蔽按下的特殊键

<script>
        //全屏，点击页面显示全屏
        window.onload = function () {
            document.getElementById("fullvoide").onclick = function () {
                var el = document.documentElement;
                var rfs = el.requestFullScreen || el.webkitRequestFullScreen || el.mozRequestFullScreen || el.msRequestFullScreen;
                if (typeof rfs != "undefined" && rfs) {
                    rfs.call(el);
                } else if (typeof window.ActiveXObject != "undefined") {
                    var wscript = new ActiveXObject("WScript.Shell");
                    if (wscript != null) {
                        wscript.SendKeys("{F11}");
                    }
                }
            }
        }
        //屏蔽鼠标右键、Ctrl+N、Shift+F10、F11、F5刷新、退格键
        document.oncontextmenu = function () {
            event.returnValue = false;
        } //屏蔽鼠标右键
        window.onhelp = function () {
            return false
        } //屏蔽F1帮助
        document.onkeydown = function () {
            if ((window.event.altKey) && ((window.event.keyCode == 37) || //屏蔽 Alt+ 方向键 ←
            (window.event.keyCode == 39))) //屏蔽 Alt+ 方向键 →
            {
                alert("不准你使用ALT+方向键前进或后退网页！");
                event.returnValue = false;
            }
            /* 注：这还不是真正地屏蔽 Alt+ 方向键，
            因为 Alt+ 方向键弹出警告框时，按住 Alt 键不放，
            用鼠标点掉警告框，这种屏蔽方法就失效了。以后若
            有哪位高手有真正屏蔽 Alt 键的方法，请告知。*/
            var k = event.keyCode;
            if ((k == 8) || //屏蔽退格删除键
            (k == 116) || //屏蔽 F5 刷新键
            (event.ctrlKey && k == 82)) { //Ctrl + R
                k = 0;
                event.returnValue = false;
            }
            if (k == 122) {
                k = 0;
                event.returnValue = false;
            }
            //屏蔽F11
            if (event.ctrlKey && k == 78) event.returnValue = false;
            //屏蔽 Ctrl+n
            if (event.shiftKey && k == 121) event.returnValue = false;
            //屏蔽 shift+F10
            if (window.event.srcElement.tagName == "A" && window.event.shiftKey)
                window.event.returnValue = false; //屏蔽 shift 加鼠标左键新开一网页
            if ((window.event.altKey) && (window.event.keyCode == 115)) { //屏蔽Alt+F4
                window.showModelessDialog("about:blank", "", "dialogWidth:1px;dialogheight:1px");
                return false;
            }
        }
    </script>