代码示例:(标识:event_key_keycode_2)
<!DOCTYPE html>
<html>
<body>

<p>在输入栏中按键盘上的任意键可以得到 Unicode 字符代码和被按下键的 Unicode 键盘代码。</p>

<p><b>注释:</b>keyCode 属性对不可打印的功能键(如 CAPS LOCK、CTRL、ESC、F12 等)的 onkeypress 事件不起作用。</p>

<input type="text" size="50" onkeypress="uniCharCode(event)" onkeydown="uniKeyCode(event)"> 

<p>onkeypress - <span id="demo"></span></p>
<p>onkeydown - <span id="demo2"></span></p>

<script>
function uniCharCode(event) {
  var char = event.which || event.keyCode;
  document.getElementById("demo").innerHTML = "The Unicode CHARACTER code is: " + char;
}

function uniKeyCode(event) {
  var key = event.keyCode;
  document.getElementById("demo2").innerHTML = "The Unicode KEY code is: " + key;
}
</script>

</body>
</html>
运行结果: