javascriptは2桁の小数を保留します.

5240 ワード

<script type="text/javascript">  
        //         
        //  :        ,     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>