单例模式

1.

var Singleton = (function () {

    var instantiated;

    function init() {

        /*这里定义单例代码*/

        return {

            publicMethod: function () {

                console.log('hello world');

            },

            publicProperty: 'test'

        };

    }



    return {

        getInstance: function () {

            if (!instantiated) {

                instantiated = init();

            }

            return instantiated;

        }

    };

})();



/*调用公有的方法来获取实例:*/

Singleton.getInstance().publicMethod();

2.

function Universe() {



    // 判断是否存在实例

    if (typeof Universe.instance === 'object') {

        return Universe.instance;

    }



    // 其它内容

    this.start_time = 0;

    this.bang = "Big";



    // 缓存

    Universe.instance = this;



    // 隐式返回this

}

3.

function Universe() {



    // 缓存的实例

    var instance = this;



    // 其它内容

    this.start_time = 0;

    this.bang = "Big";



    // 重写构造函数

    Universe = function () {

        return instance;

    };

}

4.

function Universe() {



    // 缓存实例

    var instance;



    // 重新构造函数

    Universe = function Universe() {

        return instance;

    };



    // 后期处理原型属性

    Universe.prototype = this;



    // 实例

    instance = new Universe();



    // 重设构造函数指针

    instance.constructor = Universe;



    // 其它功能

    instance.start_time = 0;

    instance.bang = "Big";



    return instance;

}

5.

var Universe;



(function () {



    var instance;



    Universe = function Universe() {



        if (instance) {

            return instance;

        }



        instance = this;



        // 其它内容

        this.start_time = 0;

        this.bang = "Big";

    };

} ());