js 获取键盘事件

<script type="text/javascript" language=JavaScript charset="UTF-8">
    document.onkeydown=function(event){
        var e = event || window.event || arguments.callee.caller.arguments[0];
        if(e && e.keyCode==27){ // 按 Esc 
            //TODO
        }
        if(e && e.keyCode==113){ // 按 F2 

            //TODO

        } 

        if(e && e.keyCode==13){ // enter 键

            //TODO

        }

    }; 
</script>