javascript浮点数计算的问题

var SysRf = SysRf || {};
SysRf.strNum = {};
//浮点数加法运算
SysRf.strNum.add = function(arg1, arg2) {  
   var r1,r2,m;  
   try{r1=arg1.toString().split(‘.‘)[1].length}catch(e){r1=0};  
   try{r2=arg2.toString().split(‘.‘)[1].length}catch(e){r2=0};  
   m=Math.pow(10,Math.max(r1,r2));  
   return (arg1*m+arg2*m)/m;

};
//浮点数乘法运算
SysRf.strNum.mul = function(arg1, arg2) {
    var m = 0, s1 = arg1 + ‘‘, s2 = arg2 + ‘‘;
    try { m += s1.split(‘.‘)[1].length } catch (e) { };
    try { m += s2.split(‘.‘)[1].length } catch (e) { };
    return parseInt(s1.replace(‘.‘, ‘‘)) * parseInt(s2.replace(‘.‘, ‘‘)) / Math.pow(10, m);
};
//浮点数除法运算
SysRf.strNum.div = function(arg1, arg2) {
    var t1 = 0, t2 = 0, r1, r2;
    try { t1 = arg1.toString().split(‘.‘)[1].length } catch (e) { }
    try { t2 = arg2.toString().split(‘.‘)[1].length } catch (e) { }
    with (Math) {
        r1 = Number(arg1.toString().replace(‘.‘, ‘‘))
        r2 = Number(arg2.toString().replace(‘.‘, ‘‘))
        return (r1 / r2) * pow(10, t2 - t1);
    }
}
//浮点数减法运算
SysRf.strNum.sub = function(arg1, arg2) {
    var r1, r2, m, n;
    try { r1 = arg1.toString().split(‘.‘)[1].length } catch (e) { r1 = 0 }
    try { r2 = arg2.toString().split(‘.‘)[1].length } catch (e) { r2 = 0 }
    m = Math.pow(10, Math.max(r1, r2));
    //动态控制精度长度  
    n = (r1 >= r2) ? r1 : r2;
    return ((arg1 * m - arg2 * m) / m).toFixed(n);
};