node2:/var/www/html/js#cat a6.html 
<p id="1">aaa</p>
<p id="2">bbb</p>
<p id="tb">xxyyzz</p>
<p id="tb">ddd</p>
<script type="text/javascript" src="jquery-2.2.2.min.js"></script>    
<script type="text/javascript" src="a6.js"></script>

node2:/var/www/html/js#cat a6.js
var item=document.getElementById("tb");// 獲取id為tb的元素(tables)
console.log(item.innerHTML);