Fixed table header to top of window upon scroll, jumps/skips a row. jQuery

Question

Please see my jsfiddle i've created to replicate my problem. http://jsfiddle.net/motocomdigital/22KFS/3/

In my project, I have created a table, which is sortable. I've used the jquery table sorter to do this which is a very simple jquery plugin. The table sorter is also included in the jsfidde. If you click the table headers, you will notice it sorts the table columns from descending to ascending.

This is fine, the problem I have is...

On my live website, the table is about 125 rows high. And I want to avoid paginating the table at all costs.

So my idea was to fix the table header upon scrolling with jQuery, which is nearly working. Please see my fiddle. The jQuery I've used to fix the header to the top of the pages works.

The problem is because the table header becomes fixed, the table shifts up a row, and makes it very glitchy.

Can anyone help me remove the glitchness, and stop it skipping a row when it reaches the top of window.

Would really appreciate any help thanks.

See jsfiddle here http://jsfiddle.net/motocomdigital/22KFS/3/

jQuery

var $window     = $(window),
    $tableHead  = $(".table-head"),
    offset      = $tableHead.offset();

$window.scroll(function() {
    if ($window.scrollTop() > offset.top) {
        $tableHead.addClass('fixed');
    } else {
        $tableHead.removeClass('fixed');
    }
});

CSS

.fixed {
   position: fixed;
   top: 0;
}

HTML

<table id="table-sorter" width="400" border="0" cellspacing="0" cellpadding="10">         
    <thead>
            <tr class="table-head">
                <th width="100" height="18" valign="middle">Number</th>
                <th width="100" height="18" valign="middle">First Name</th>
                <th width="100" height="18" valign="middle">Surname</th>
                <th width="100" height="18" valign="middle">System</th>
            </tr>
    </thead>
    <tbody>
            <tr>
                <td>1</td>
                <td>John</td>
                <td>Smith</td>
                <td>Wordpress</td>     
            </tr>

            ... ...

    </tbody>
</table>

Answer 1

Solved your problem. In case you hadn't realised already, the reason it jumps is because you are essentially removing the header row from the table when you make it position fixed, so the rest of the table jumps up to fill the gap.

The solution? Well, it's up for debate. To prove my point, all I've done is add a new temporary header when you make the actual header fixed. This keeps the table in place and allows the header to move down. When you scroll back up, that temporary header then gets removed.

Is this the best way? Not sure, you maybe want to clone the real header as a temporary solution, just in case of graphical glitches. This would also mean that in case of headers with multiple lines (therefore pushing the height down), the effect would be maintained as it's taking an exact clone.

Anyway, on with the code: http://jsfiddle.net/chricholson/22KFS/5/

$("#table-sorter").tablesorter({
 widgets: ['zebra']
});


var $window     = $(window),
    $tableHead  = $(".table-head"),
    offset      = $tableHead.offset();

$window.scroll(function() {


    if ($window.scrollTop() > offset.top) {
        $tableHead.addClass('fixed');
        if ($('#table-sorter thead tr.temp').length <= 0){
            $('#table-sorter thead').append('<tr class="temp"><td>hello</td></tr>');
        }
    } else {
        $tableHead.removeClass('fixed');
        $('tr.temp').remove();
    }


}); 

​ Good luck.

EDIT

Here's the working product using clone() http://jsfiddle.net/chricholson/22KFS/8/

Code:

$("#table-sorter").tablesorter({
     widgets: ['zebra']
});


var $window     = $(window),
    $tableHead  = $(".table-head"),
    offset      = $tableHead.offset();

$window.scroll(function() {


    if ($window.scrollTop() > offset.top) {
        $tableHead.addClass('fixed');
        if ($('#table-sorter thead tr.temp').length <= 0){
            $tableHead.clone().appendTo('#table-sorter thead').removeClass('fixed').addClass('temp');
        }
    } else {
        $tableHead.removeClass('fixed');
        $('tr.temp').remove();
    }


});    ​