SOURCE

// 单体模式
var Singleton = function(name){
    this.name = name;
    this.instance = null;
};
Singleton.prototype.getName = function(){
    return this.name;
}
// 获取实例对象
function getInstance(name) {
    if(!this.instance) {
        this.instance = new Singleton(name);
    }
    return this.instance;
}
// 测试单体模式的实例
var a = getInstance("aa");
var b = getInstance("bb");
console.log(a);
console.log(b);
console.log(a == b)