Javascript中singleton的实现

      最好的实现：

var langzi = window.langzi || {};
langzi.singleton = window.langzi.singleton || (function () {
    var instance = null;
    var constructor = function () {
        return {
            id: 1,
            name: "test",
            getMessage: function () {
                console.log("id:" + this.id + ", name:" + this.name);
            }
        };
    };

    return {
        getInstance: function () {
            if (instance == null) {
                instance = constructor();
            }
            return instance;
        }
    };
} ());

 测试代码如下：

// test
var s1 = langzi.singleton.getInstance();
var s2 = langzi.singleton.getInstance();
s1.getMessage();
s2.getMessage();
console.log(s1 == s2);

      按照Pro Javascript Design Pattern作者的说法，namespace都是singleton的应用。从广义来说，个人认为确实是的，但既然说到singleton，我觉得应该还是我上面的例子最具有代表性。