JavaScript jsは正確で、小数点以下の方法を保留します.

4872 ワード

//         

        //  :        ,     2   

        function toDecimal(x) {  

            var f = parseFloat(x);  

            if (isNaN(f)) {  

                return;  

            }  

            f = Math.round(x*100)/100;  

            return f;  

        }  

  

  

        //   2   , :2,  2    00. 2.00  

        function toDecimal2(x) {  

            var f = parseFloat(x);  

            if (isNaN(f)) {  

                return false;  

            }  

            var f = Math.round(x*100)/100;  

            var s = f.toString();  

            var rs = s.indexOf('.');  

            if (rs < 0) {  

                rs = s.length;  

                s += '.';  

            }  

            while (s.length <= rs + 2) {  

                s += '0';  

            }  

            return s;  

        }  

          

        function fomatFloat(src,pos){     

             return Math.round(src*Math.pow(10, pos))/Math.pow(10, pos);     

        }  

        //      

         alert("  2   :" + toDecimal(3.14159267));  

        alert("    2   :" + toDecimal2(3.14159267));  

        alert("  2   :" + toDecimal(3.14559267));  

        alert("    2   :" + toDecimal2(3.15159267));  

        alert("  2   :" + fomatFloat(3.14559267, 2));  

        alert("  1   :" + fomatFloat(3.15159267, 1));  

          

        //      

         alert("  2   :" + 1000.003.toFixed(2));  

        alert("  1   :" + 1000.08.toFixed(1));  

        alert("  1   :" + 1000.04.toFixed(1));  

        alert("  1   :" + 1000.05.toFixed(1));  

          

        //      

         alert(3.1415.toExponential(2));  

        alert(3.1455.toExponential(2));  

        alert(3.1445.toExponential(2));  

        alert(3.1465.toExponential(2));  

        alert(3.1665.toExponential(1));  

        //   n ,  n   

         alert("       2 " + 3.1415.toPrecision(2));  

        alert("       3 " + 3.1465.toPrecision(3));  

        alert("       2 " + 3.1415.toPrecision(2));  

        alert("       2 " + 3.1455.toPrecision(2));  

        alert("       5 " + 3.141592679287.toPrecision(5));  

    </script>