JavaScript设计模式详解：揭示模块与单例模式

<script>
var myRevealingModule = function () {
    var privateVar = "Ren Cherry",
            publicVar = "Hey there";
    function privateFunction() {
            console.log("Name:"+privateVar);
    }
    function publicSetName(strName) {
            privateName = strName;
    }
    function publicGetName() {
            privateFunction();
    }
    //将暴露的公有指针指向到私有函数和属性上
    return {
            setName: publicSetName,
            greeting: publicvar,
            getName: publicGetName
    };
}();
myRevealingModule.setName("Paul Kinlan");
</script>

<script type="text/javascript">
var mySingleton = (function () {
        //实例保持了singleton 的一个引用
        var instance;
        function init() {
                //singleton
                //私有方法和变量
                function privateMethod() {
                        console.log("I am private");
                }
                var privateVariable = "I am also private";
                var privateRandomNumber = Math.random();
                return {
                        //公有方法和变量
                        publicMethod: function () {
                                console.log("The public can see me!");
                        },
                        publicProperty: "I am also public",
                        getRandomNumber: function() {
                                return privateRandomNumber;
                        }
                };
        };
        return {
                //获取singleton 的实例，如果存在就返回，不存在就创建新实例
                getInstance: function() {
                        if(!instance) {
                                instance = init();
                        }
                        return instance;
                }
        };
})();
var singleA = mySingleton.getInstance();
var singleB = mySingleton.getInstance();
console.log(singleA.getRandomNumber()===singleB.getRandomNumber());//true
</script>

<script type="text/javascript">
var SingletonTester = (function() {
        //options: 包含singleton所需配置信息的对象
        //var options = {name:"test",pointX:5};
        function Singleton(options) {
                //如果未提供options,则设置为空对象
                options = options || {};
                //为singleton设置一些属性
                this.name = "SingletonTester";
                this.pointX = options.pointX || 6;
                this.pointY = options.pointY || 10;
        }
        //实例持有者
        var instance;
        //静态变量和方法的模拟
        var _static = {
                name: "SingletonTester",
                //获取实例的方法，返回singleton对象的singleton实例
                getInstance: function(options) {
                        if(instance === undefined) {
                                instance = new Singleton(options);
                        }
                        return instance;
                };
                return _static;
        }
})();
var singletonTest = SingletonTester.getInstance({
        pointX: 5
});
console.log(singletonTest.pointX);//5
</script>