方法一：(ie下有问题)

     <script  type= "text/javascript">

         var   num_s = "1232134456.546 ";alert(parseFloat(num_s).toLocaleString());

     </script>

方法二： 

 <script type="text/javascript">

 　　function format_number(n){

   var b=parseInt(n).toString();

   var len=b.length;

   if(len<=3){return b;}

   var r=len%3;

   return r>0?b.slice(0,r)+","+b.slice(r,len).match(/\d{3}/g).join(","):b.slice(r,len).match(/\d{3}/g).join(",");

 }

var a="53669988.000";

alert(format_number(a));

alert(format_number("wahh"));

alert(format_number(0));

alert(format_number(6698.0023));

</script>