                        課程
                    
                        /前端開發
                        
                            /jQuery
                        
                        /jQuery基礎 (一)—樣式篇

DOM對象和jQuery對象轉化

<html>
<head>
<script?type="text/javascript">
/*function?getInnerHTML()
??{
??alert(document.getElementById("tr1").innerHTML);
??}*/
</script>
<script?type="text/javascript"?src="jquery-1.11.1.min.js"></script>
<script?type="text/javascript">
????var?$sc?=?$("#tr1");
????var?cr?=?$sc.get(0);
????alert(cr);
</script>
</head>
<body>

<table?border="1">
????<tr?id="tr1">
????????<th>Firstname</th>
????????<th>Lastname</th>
????</tr>
????<tr?id="tr2">
????????<td>Peter</td>
????????<td>Griffin</td>
????</tr>
</table>

<input?type="button"?onclick="getInnerHTML()"?value="Alert?innerHTML?of?table?row"?/>

</body>
</html>

純小白，請問alert（cr）中的cr指的是什么，為什么網頁上彈出的對話框顯示Undifined