我想用這個方式bytagname，為啥輸出不了，哪里錯了，來個大神
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>無標題文檔</title>
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? <div><b id="oldnode">JavaScript</b>是一個很常用的技術(shù)，為網(wǎng)頁添加動態(tài)效果。</div>
? <a href="javascript:replaceMessage()"> 將加粗改為斜體</a>
?
??? <script type="text/javascript">
????? function replaceMessage(){
???????? var newnode=document.createElement("i");
???????? var oldNode=document.getElementSByTagName("b");
???????? var oldHTML=oldnode.innerHTML;
???????? oldNode.parentNode.replaceChild(newnode,oldNode);
???????? newnode.innerHTML=oldHTML;
?????? }?? ?
? </script>
?</body>
</html>
2017-09-08
var oldNode=document.getElementSByTagName("b");
getElementSByTagName ? ? ? ?s大寫了