jQuery Simple Example

HTML

<script src="//www.addressfinder.co.nz/assets/v2/widget.js"></script>
<table>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
  <td>b</td>
  <td>c</td>
</tr>
<tr>
  <td>a</td>
 ...

CSS

table  tr  td:first-child{background:red;}

table tr:first-child{
  background:green;
  position: absolute;
}

JavaScript

$(function() {
  var win = $(window),
    body = $(document.body),

    planningHead = body.find('table tr:first-child').first();




        $(window).scroll(function () {
            var self = this;

            throttle(function () {

                    planningHead.css("top", $(self).scrollTop() + 50 + "px");
            
            }(), 200);
        });

        function throttle(callback, limit) {
            var wait = false;                 // Initially, we're not waiting
            return function () {              // We return a throttled function
                if (!wait) {                  // If we're not waiting
                    callback.call();          // Execute users function
                    wait = true;              // Prevent future invocations
                    setTimeout(function () {  // After a period of time
                        wait = false;         // And allow future invocations
                    }, limit);
                }
            }
        }
});