把简单运算方法挂在到Number原型上

代码

const floatObj = function () {
        function sum(n1, n2) {
            var n1FloatLength, n2FloatLength;
            try {
                n1FloatLength = n1.toString().split('.')[1].length;
            } catch (e) {
                n1FloatLength = 0;
            }
            try {
                n2FloatLength = n2.toString().split('.')[1].length;
            } catch (e) {
                n2FloatLength = 0;
            }
            var m = Math.pow(10, Math.max(n1FloatLength, n2FloatLength));
            return Math.round(n1 * m + n2 * m) / m;
        }

        function mul(a, b) {
            var c = 0,
                d = a.toString(),
                e = b.toString();
            try {
                c += d.split(".")[1].length;
            } catch (f) { }
            try {
                c += e.split(".")[1].length;
            } catch (f) { }
            return Number(d.replace(".", "")) * Number(e.replace(".", "")) / Math.pow(10, c);
        }

        function division(a, b) {
            var c, d, e = 0,
                f = 0;
            try {
                e = a.toString().split(".")[1].length;
            } catch (g) { }
            try {
                f = b.toString().split(".")[1].length;
            } catch (g) { }
            return c = Number(a.toString().replace(".", "")), d = Number(b.toString().replace(".", "")), mul(c / d, Math.pow(10, f - e));
        }
        return {
            add: sum,
            subtract: function (n1, n2) { return sum(n1, -n2); },
            multiply: mul,
            divide: division
        }
    }();
    Number.prototype.add = function (arg) {
        return floatObj.add(this, arg);
    }
    Number.prototype.subtract = function (arg) {
        return floatObj.subtract(this, arg);
    }
    Number.prototype.multiply = function (arg) {
        return floatObj.multiply(this, arg);
    }
    Number.prototype.divide = function (arg) {
        return floatObj.divide(this, arg);
    }

使用示例

const a = 1
const b = 2
let result = {
   addValue: undefined,  // +
   subtractValue: undefined, // -
   multiplyValue: undefined, // *
   divideValue: undefined, // /
}

result.addValue = a['add']b
result.subtractValue= a['subtract']b
result.multiplyValue= a['multiply']b
result.divideValue= a['divide']b