<script type="text/javascript">

            /*四舍五入*/

            functionround(v,e){

                var t=1;

                for(;e>0;t*=10,e--);

                for(;e<0;t/=10,e++);

                return Math.round(v*t)/t;

            }

            document.write(round(2.38769162961926,4));

        </script>