JS：如何获取表中的肢体索引

Question

I have a table with many tbodies inside. For example:

<table id="tableId">
 <tbody id="tbodyId">
   <tr><td>1</td></tr>
 </tbody>
 <tbody>
   <tr><td>2</td></tr>
 </tbody>
 <tbody>
   <tr><td>3</td></tr>
 </tbody>
</table>

I need these tbody for grouping rows with span. How can I get certain tbody index in table via js? I mean:

var tbody=....;
var table=....;
var tbodyIndex=?

For example, for rows we can use rowIndex , but for tbodies?

EDIT Special edit for some users:

var tbody=document.getElementById("tbodyId");
var table=document.getElementById("tableId");
var tbodyIndex=?

Answer 1

You could use:

var tbody=document.getElementById("tbodyId");
var table=document.getElementById("tableId");
var tbodyIndex= [].slice.call(table.tBodies).indexOf(tbody); // [].slice.call() to convert HTML collection to array

-DEMO-