■<=30
■>30
■>50
■>60
■>100
■>300
■>400

<script src="../1.2.6/jquery-1.2.6.js" type="text/javascript"></script>

<script type="text/javascript">
//:myComp
jQuery.extend(jQuery.expr[":"], {
 myComp  : function(a,i,m){ 
   var b = Number(
    (a.textContent||a.innerText||jQuery(a).text()||"")
        .replace(/,/g,'')
     );
   return typeof b=='number'? eval(b+m[3]):false;
 }

});

</script>

<div id="test1">
<table id="testTable" border="1">
<tr><td>Id</td><td>test1</td><td>test2</td><td>test3</td></tr>
<tr><td>a</td><td>234</td><td>24</td><td>37</td></tr>
<tr><td>b</td><td>555</td><td>112</td><td>50</td></tr>
<tr><td>c</td><td>333</td><td>88</td><td>60</td></tr>
<tr><td>d</td><td>256</td><td>15</td><td>72</td></tr>
</table>

<script type="text/javascript">
jQuery(function($){
 $('#test1')
  .find('td:myComp(<=30)').css('background','#f00').end()
  .find('td:myComp(>30)').css('background','#f40').end()
  .find('td:myComp(>50)').css('background','#f60').end()
  .find('td:myComp(>60)').css('background','#f80').end()
  .find('td:myComp(>100)').css('background','#fa0').end()
  .find('td:myComp(>300)').css('background','#fd0').end()
  .find('td:myComp(>400)').css('background','#ff0').end()
});
</script>