<html>
<head>
<script type="text/javascript">
function writeMessage()
{
document.forms[0].mySecondInput.value=document.forms[0].myInput.value
}
</script>
</head>
<body>
<p>当键盘按键上升时，会发生 onkeyup 事件。</p>
<form>
请编写一条消息：<br />
<input type="text" name="myInput" onkeyup="writeMessage()" size="20">
<input type="text" name="mySecondInput" size="20">
</form>
</body>
</html>