javascript精度计算

function accDiv(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);
}
}
Number.prototype.div = function(arg) {
return accDiv(this, arg);
}

function accMul(arg1, arg2) {
var m = 0, s1 = arg1.toString(), s2 = arg2.toString();
try {
m += s1.split(".")[1].length
} catch (e) {
}
try {
m += s2.split(".")[1].length
} catch (e) {
}
return Number(s1.replace(".", "")) * Number(s2.replace(".", "")) / Math.pow(10, m)
}

Number.prototype.mul = function(arg) {
return accMul(arg, this);
}

function accAdd(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
}
// 给Number类型增加一个add方法，调用起来更加方便。
Number.prototype.add = function(arg) {
return accAdd(arg, this);
}

function Subtr(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);
}