gistfile1.js

// Define a custom formatter to format Numbers as US currency format, and if negative, to 
//   set color to RED and surround with parenthesis;
//    Example:     ( $ 12,345.67 )   in red
//   Note: Function needs to be defined BEFORE the Column definitions that use it !!
var fmtNegCurrency = function(elCell, oRec, oCol, oData) {
   var num_prefix='',
       num_suffix='';
                
    if ( oData < 0.0 ) {
        YAHOO.util.Dom.setStyle(elCell,'color','red');
        num_prefix = '(';
        num_suffix = ')';
    }
       
   // define format configuration for Number.format function ...
   var fmtCurrency = {   
       prefix : '$ ',    
       thousandsSeparator: ',',
       decimalSeparator: '.',    
       decimalPlaces: 2
   }

   // "format" the number using YAHOO.util.Number.format ... (see API for details)
   var num_fmt = YAHOO.util.Number.format( oData, fmtCurrency );

   // Insert the formatted data in the Cell, put prefix / suffix on if defined .

   elCell.innerHTML = num_prefix + num_fmt + num_suffix;  
}


// Use the formatter in your DataTable column ...
var myColumns = [
   // your Column names here ...
   { key:'totals', label:'Net Totals', formatter:fmtNegCurrency }
   // other column names ....
];