Question

I want to remove duplicate cells of a column.

<table id="test" border="1">
    <tr>
    <td>test1<td>
    <td>test2<td>
    <td>test3<td>
    </tr>
      <tr>
    <td>test4<td>
    <td>test2<td>
    <td>test5<td>
    </tr>
    <tr>
    <td>test6<td>
    <td>test2<td>
    <td>test5<td>
    </tr>
          <tr>
    <td>test6<td>
    <td>test8<td>
    <td>test9<td>
    </tr>
    </table>​​​

output
------
test1        test2        test3    
test4        test2        test5    
test6        test2        test9    
test6        test8        test9    


I want in this format
---------------------
test1        test2        test3    
test4                     test5     
test6                     test9    
             test8           

​

Answer 1

This only removes duplicate text across columns. It works because elements are selected in document order:

var seen = {};
$('#test td').each(function() {
    // Encode column and content information.
    var key =  $(this).index() +  $(this).text();
    if (seen[key]) {
        $(this).text('');
    }
    else {
        seen[key] = true;
    }
})​;

It probably won’t work though if you have cells spanning multiple columns.

Slightly adjusted DEMO.

Update: For consecutive cells only. The idea is to keep track of the previous value that was seen in one column.

var seen = {};
$('#test td').each(function() {
    var index =  $(this).index();
    var txt = $(this).text();
    if (seen[index] === txt) {
        $(this).text('');
    }
    else {
        seen[index] = txt;
    }
})​;

DEMO (note test5 in the right column)