Introduction
 
W3C has introduced a new "template" tag that provides a mechanism to define HTML markup fragments as prototypes. In practice, a template can be used to insert fragments of HTML code into your page, for example
- <template id="rowTemplate">  
- <tr>  
- <td class="record"></td>  
- <td></td>  
- <td></td>  
- </tr>  
- </template>   
Features
 
The following are the features of the template tag:
     - The template code can be defined nearly anywhere; the head, body or even a frameset. 
- Templates will not be displayed
- Templates are not considered to be part of the document, in other words using document.getElementById(“mytablerow”) will not return child nodes.
- Templates are inactive until used, in other words, enclosed images will not download, media will not play, scripts will not run, and so on.
Using templates
 
To use a template, it must be cloned and inserted into the DOM. For example, assuming the following HTML:
- <table id="testTable">  
-     <thead>  
-         <tr>  
-             <td>  
-                 ID  
-             </td>  
-             <td>  
-                 name  
-             </td>  
-             <td>  
-                 twitter  
-             </td>  
-         </tr>  
-     </thead>  
-     <tbody>  
-         <!-- rows to be appended here -->  
-     </tbody>  
- </table>  
- <!-- row template -->  
- <template id="rowTemplate">  
- <tr>  
- <td class="record"></td>  
- <td></td>  
- <td></td>  
- </tr>  
- </template>   
 
Use the following to clone the new row and append it to the table in JavaScript:
-   
- var t = document.querySelector("#testTable tbody"),  
-     row = document.getElementById("rowTemplate");  
-   
- var td = row.getElementsByTagName("td");  
- td[0].textContent = "1";  
- td[1].textContent = "Sunny";  
- td[2].textContent = "@sunny_delhi";  
-   
- t.appendChild(row.content.cloneNode(true));  
 
Q: Can we use templates?
 
A: Not yet. For now, it’s supported in the latest version of Chrome and Firefox nightly builds but yes, there’s a shim demonstrated that you can use as a workaround until it is implemented by all prominent browsers. It probably works in IE also.
 
Shim DemoLink: 
jsfiddle
 
Separation of HTML code and JavaScript is a good idea!