这代码有问题吗。为什么点击按钮没反应的
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<input type="button" value="点击" onClick="showState()"/>
<script>
function showState(){
alert("altKey:"+window.event.altKey
+"\nshiftKey:"+window.event.shiftKey
+"\nctrlKey:"+window.event.ctrlKey);
}</script>
</body>
</html>