Question

我对JavaScript非常陌生，并认为一个好的任务将通过Kent Beck的TDD By Example工作，并用JavaScript代替Java。简单的继承似乎很神秘，因为有很多关于如何实现这一点的意见，例如这个stackoverflow条目：JavaScript Inheritance

我不想在C ++ / Java中模仿继承，即使我最终使用了库，我也想知道如何自己正确地实现它。请查看以下简单的货币示例，该示例来自在JavaScript和Jasmine中重写的TDD By Example，并且忽略代码的微不足道，请告诉我这是否是一种正确的技术。

// currency.js

var CommonCurrency = function() {

    function Currency(amount){
        this.amount = amount;
    }

    Currency.prototype.times = function(multiplier){
        return new Currency(this.amount*multiplier);
    };

    function Dollar(amount){
        Currency.call(this, amount);
    }
    Dollar.prototype = Object.create(Currency.prototype);
    Dollar.prototype.constructor = Dollar;

    function Pound(amount){
        Currency.call(this, amount);
    }
    Pound.prototype = Object.create(Currency.prototype);
    Pound.prototype.constructor = Pound;

    return {
        Dollar: Dollar,
        Pound: Pound 
    }
}();

module.exports = CommonCurrency;

spec文件：

// spec/currency-spec.js

var currency = require("../currency");

describe("testCurrency", function() {
    describe("testDollar", function() {     
        var fiveDollars = new currency.Dollar(5);

        it("should multiply dollar amount by given parameter", function() {
            var product = fiveDollars.times(2);
            expect(product.amount).toBe(10);
        });

        it("should return new dollar amount and not multiply last result ", function() {
            var product = fiveDollars.times(3);
            expect(product.amount).toBe(15);
        });
    });

    describe("testPound", function() {
        var fivePounds;

        it("should multiply pound amount by given parameter", function() {
            var product = fivePounds.times(2);
            expect(product.amount).toBe(10);
        });

        it("should return new pound amount and not multiply last result ", function() {
            var product = fivePounds.times(3);
            expect(product.amount).toBe(15);
        });
    });  
});

感谢。

JavaScript中实用，正确的继承

0 个答案: