javascript 对象方法未定义

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所以，我是 JS 新手，我在对象方法方面遇到了一些问题。构建对象原型(prototype)中的方法 buy() 应该执行我为其定义的操作，但它显示“未定义”。

var bitcoins=9000; //for example
var bitcoinsps=0;
    function building(price, bps, name) {
    this.price = price;
    this.bps = bps;
    this.name = name;
    this.amount = 0;
}
building.prototype.buy = function buy() {

    if (bitcoins >= building.price) {
        amount++;
        bitcoins -= price;
        price *= 1.15;
        bitcoinsps += bps;
    }
};

注意:是的，我确实创建了一个实例。

我在调用变量时尝试了“building.blabla”和“this.blabla”，但没有任何反应。怎么了？

编辑:我的新代码:

var bitcoins = 0;
var bitcoinsps = 0;
var build = new Array();

function building(price, bps, name) {
    this.price = price;
    this.bps = bps;
    this.name = name;
    this.amount = 0;

}
building.prototype.buy = function() {

    if (bitcoins >= building.price) {
        this.amount++;
        bitcoins -= this.price;
        this.price *= 1.15;
        bitcoinsps += this.bps;
    }
};
    build[1] = new building(70, 1, "Junky laptop");
    build[2] = new building(300, 4, "Average PC");
    build[3] = new building(1000, 15, "Gaming PC");
    build[4] = new building(5000, 70, "Dedicated Hardware");
    build[5] = new building(24000, 300, "Small cluster computer");
    build[6] = new building(100000, 1000, "Medium cluster computer");
    build[7] = new building(500000, 4500, "Large cluster computer");

Answer 1

buy() 必须使用this.blabla。因此，像这样改变它的实现:

building.prototype.buy = function buy() {
    if (bitcoins >= this.price) {
        this.amount++;
        bitcoins -= this.price;
        this.price *= 1.15;
        bitcoinsps += this.bps;
    }
};

此外，您必须使用“new”创建一个建筑实例。例如:

var b = new building(1, 2, 'fred');
b.buy();