关于js计算的问题

js做这种高精度的计算需要换种方式进行 eg：

//减法

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));
//动态控制精度长度
n = (r1 >= r2) ? r1 : r2;
return parseFloat(((arg1 * m - arg2 * m) / m).toFixed(n));
}
//加法
function add(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
}
//乘法
function mul(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)
}
//除法
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) { }
with (Math) {
r1 = Number(arg1.toString().replace('.', ''))
r2 = Number(arg2.toString().replace('.', ''))
return (r1 / r2) * pow(10, t2 - t1);
}
}

var Amt = Number("169805.10");
var Amt1 = Number("84281.20");

alert(add(Amt1 ,Amt));

var Amt = Number("69805.10");
var Amt1 = Number("184281.20");
alert(add(Amt1 ,Amt));

这样就ok了。。。