js保留两位小数的函数有哪些

//浮点数保留两位小数

          //1.功能：将浮点数四舍五入，取小数点后2位

          function toDecimal(x) {

           var f = parseFloat(x);

           if (isNaN(f)) {

            return;

           }

           f = Math.round(x*100)/100;

           return f;

          }

          console.log(toDecimal(3.1465926)); // 3.15

          console.log(typeof toDecimal(3.1415926)); //number

//2.强制保留2位小数，如：2，会在2后面补上00.即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;

          }

          console.log(toDecimal2(3.1)); // 3.10

          console.log(typeof toDecimal2(3.1415926)); //string

// 3.保留两位小数 浮点数四舍五入 位数不够 不补0

          function fomatFloat(src,pos){

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

          }

           console.log(fomatFloat(3.12645,2)); // 3.13

          console.log(typeof fomatFloat(3.1415926)); //numbe