js中保证小数运算精度的解决

function Add(a, b) {
var str1 = a.toString(),str2 = b.toString(),r1,r2,m;
try{r1= str1.split('.')[1].length;}catch(e){ r1 = 0; }
try{r2= str2.split('.')[1].length;}catch(e){ r2 = 0; }
m = Math.pow(10,Math.max(r1,r2));
return (a*m + b*m)/m
}

function Sub(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));
//last modify by deeka
//动态控制精度长度
n = (r1 >= r2) ? r1 : r2;
return ((arg1 * m - arg2 * m) / m).toFixed(n);
}

function Mul(a, b) {
var str1 = a.toString(),str2 = b.toString(),m=0;
try{m += str1.split('.')[1].length;}catch(e){}
try{m += str2.split('.')[1].length;}catch(e){}
return Number(str1.replace(".", "")) * Number(str2.replace(".", "")) / Math.pow(10, m)
}

function Div(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) {}
r1 = Number(arg1.toString().replace(".", ""));
r2 = Number(arg2.toString().replace(".", ""));
return (r1 / r2) * Math.pow(10, t2 - t1);
}