Question

Suppose this is my table:

<table>
    <tr id="a">
       <TD>a</TD>
    </tr>
    <tr id="b">
       <TD>b</TD>
    </tr>
</table>

How can I get row id using the row index from a table?

Above is just an example where id is static but in my case my id is dynamic, so I can’t use
document.getElementById().

Answer 1

Assuming you have only one table on your page:

document.getElementsByTagName("tr")[index].id;

Preferably though, you’d give your table a id, though, and get your row like this:

<table id="tableId">
    <tr id="a">
        <td>a</td>
    </tr>
    <tr id="b">
        <td>b</td>
    </tr>
</table>

var table = document.getElementById("tableId");
var row = table.rows[index];
console.log(row.id);

This way, you can be certain you don’t get any interference, if you have multiple tables in your page.