​x
 
<!DOCTYPE html>
<html>
<head>
<script>
function whichButton(event) {
  document.getElementById("demo").innerHTML = event.keyCode;
}
</script>
</head>
​
<body onkeyup="whichButton(event)">
​
<p><b>注释：</b>尝试此示例时，请确保右框架具有焦点！</p>
​
<p>单击此页面，然后按键盘上的键。</p>
​
<p id="demo"></p>
​
</body>
</html>
​