Thanks! Yes, I get confused sometimes on what $(this) really is sometimes.
Here's the final code. Works great... PS this is for the TableSorter plugin, which hates commas: $(document).ready(function() { $("table").tablesorter({headers: { 3: { sorter: "digit" },4: { sorter: "digit" },5: { sorter: "digit" },6: { sorter: "digit" } , 7: { sorter: "digit" },8: { sorter: "digit" },9: { sorter: "digit" },10: { sorter: "digit" },11: { sorter: "digit" },12: { sorter: "digit" }} , widgets: ['zebra'] }); $(".commas").addCommas(); } ); jQuery.fn.addCommas = function() { this.each(function(){ nStr = $(this).html() + ''; x = nStr.split('.'); x1 = x[0]; x2 = x.length > 1 ? '.' + x[1] : ''; var rgx = /(\d+)(\d{3})/; while (rgx.test(x1)) { x1 = x1.replace(rgx, '$1' + ',' + '$2'); } $(this).html(x1 + x2); }); }