javascript - 面向对象的 JavaScript 帮助

Question

我有以下代码:

var HD = function() { };

HD.Car = (function() {
    var _date = "09/07/2010";
    return {
        Make: undefined,
        Model: undefined,
        showMakeAndModel: function() {
            document.write(this.Make + " " + 
                           this.Model + 
                           " (data correct as of " + _date + ")");
            }
        };
    })();

var bert = new HD.Car();
bert.Make = "Ford";
bert.Model = "Capri";
window.onload = bert.showMakeAndModel();

并得到以下错误:

HD.Car is not a constructor

我想做的就是测试(学习)带有闭包的“单例模式”(对于私有(private)成员)，所以不是“真实”的例子，但我正在阅读的书建议这样做

所以有点困惑 - 任何帮助将不胜感激..罗布

Answer 1

您在 HD.Car 类定义周围有一些不正确的 ()()。这个固定样本有效:

var HD = function() { }; 

HD.Car = function() { 
    var _date = "09/07/2010"; 
    return { 
        Make: undefined, 
        Model: undefined, 
        showMakeAndModel: function() { 
            document.write(this.Make + " " +  
                           this.Model +  
                           " (data correct as of " + _date + ")"); 
            } 
        }; 
    }; 

var bert = new HD.Car(); 
bert.Make = "Ford"; 
bert.Model = "Capri"; 
window.onload = bert.showMakeAndModel();