Question

Is there a simple way to count the unique cells in a column (or row) in an HTML table with jQuery or plain Javascript?

Example: (table with only one column)

melon
banana
melon
strawberry

The counter would be 3.

Answer 1

Try this:

var a = {}, l = 0;
$('table tr td:first-child').each(function(){
    if (!a[$(this).text()]) {
        l++;
        a[$(this).text()] = true;
    }
});

alert(l);

For HTML:

<table>
    <tr><td>melon</td><td></td></tr>
    <tr><td>banana</td><td></td></tr>
    <tr><td>melon</td><td></td></tr>
    <tr><td>strawberry</td><td></td></tr>
</table>

This will work for first column. If you want to count values in second column you would use selector table tr td:first-child+td, for third table tr td:first-child+td+td, etc.

Working example: http://jsfiddle.net/7K64j/1/