js全屏解決方案

<script type="text/javascript">
        document.onkeydown=function(e){
            e = e|| window.event || arguments.callee.caller.arguments[0]; 
            if(e && e.keyCode==122){
                //fullScreen();
                document.getElementById('bt').onclick();
                e.preventDefault();
                e.stopPropagation();
            }
        }
        function FullScreen(el) {
            var isFullscreen = document.fullScreen || document.mozFullScreen || document.webkitIsFullScreen;
            if (!isFullscreen) {//進入全屏,多重短路表達式
                (el.requestFullscreen && el.requestFullscreen()) ||
                    (el.mozRequestFullScreen && el.mozRequestFullScreen()) ||
                    (el.webkitRequestFullscreen && el.webkitRequestFullscreen()) || 
                    (el.msRequestFullscreen && el.msRequestFullscreen());

            } else {	//退出全屏,三目運算符
                document.exitFullscreen ? document.exitFullscreen() :
                    document.mozCancelFullScreen ? document.mozCancelFullScreen() :
                        document.webkitExitFullscreen ? document.webkitExitFullscreen() : '';
            }
        }
        function toggleFullScreen(e) {
            var el = e.srcElement || e.target;//target兼容Firefox
            el.innerHTML == '點我全屏' ? el.innerHTML = '退出全屏' : el.innerHTML = '點我全屏';
            FullScreen(el);
        }
    </script>
    <button id="bt" onclick="toggleFullScreen(event)">點我全屏</button>