代码示例:(标识:event_key_key)
<!DOCTYPE html>
<html>
<body>

<p>在输入字段中按键盘上的某个键。</p>

<input type="text" size="40" onkeydown="myFunction(event)">

<p id="demo"></p>

<script>
function myFunction(event) {
  var x = event.key;
  document.getElementById("demo").innerHTML = "The pressed key was: " + x;
}
</script>

</body>
</html>
运行结果: