Question

Let’s say i have a table like this:

<table cellpadding="0" cellspacing="0" border="0" class="display" id="selection">
    <th>Values</th>
    <th>Average</th>
    <tbody>
        <tr>
            <td>5</td>
            <td></td>       
        </tr>   
        <tr>
            <td>0.9</td>
            <td></td>       
        </tr>  
        <tr>
            <td>2</td>
            <td></td>       
        </tr>  
        <tr>
            <td>6</td>
            <td></td>       
        </tr>  
    </tbody>
</table>

I want to calculate average of column “values” and put it in each td of the average column using Jquery. The result shoud be like this picture:

Please note that i filter results in the table with a search box and the number of rows will change each time the user searches.

Answer 1

var sum = 0,
    count = -1,
    all = $('#selection > tbody > tr');
all.each(function() {
    sum += +$('td:eq(0)', this).text();
    count++;
});
all.find('td:eq(1)').text((sum / count).toFixed(3));

Working sample

Note

+$('td:eq(0)', this).text(), here the beginning + sing convert the text to number.