JavaScript动态修改网页元素内容的方法

<script type="text/javascript">
function showCard() {
 var message = document.getElementById("CCN").value;
 var element = document.getElementById("mycreditcardnumber");
 element.textContent = message;
//for Firefox
 element.innerHTML = message;
//for IE (why can't we all just get along?)
 return true;
}
</script>
<form name="dynamic" method="get">
<span>Enter Your Credit Card Number:</span>
<input type="text" id="CCN" name="CCN" value="CCN" />
<input type="button" value="submit" onclick="showCard()" />
</form>
<p>Verify your Credit Card Number:
 <span id="mycreditcardnumber">0000-00-0000-00 </span>
</p>