//加法
Number.prototype.add = function (arg) {
var r1 = 0, r2 = 0, m;
//获取小数的位数并取最大值
try { r1 = this.toString().split(".")[1].length } catch (e) { }
try { r2 = arg.toString().split(".")[1].length } catch (e) { }
m = Math.pow(10, Math.max(r1, r2))
return (this * m + arg * m) / m
}
//减法
Number.prototype.sub = function (arg) {
return this.add(-arg);
}
//乘法
Number.prototype.mul = function (arg) {
var m = 0, s1 = this.toString(), s2 = arg.toString();
//小数位数相加
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
Number.prototype.div = function (arg) {
var t1 = 0, t2 = 0, r1, r2;
try { t1 = this.toString().split(".")[1].length } catch (e) { }
try { t2 = arg.toString().split(".")[1].length } catch (e) { }
//将小数点去掉转换为整数
r1 = Number(this.toString().replace(".", ""))
r2 = Number(arg.toString().replace(".", ""))
return (r1 / r2) * Math.pow(10, t2 - t1);
}
