SOURCE

class SingletonLogin{
    constructor (name, password){
         this.name = name
         this.password =password
    }
  static  getInstance(name,password){
      //判断是否已经被创建， 若创建则返回旧对象
      if(!this.instance){
          this.instance = new SingletonLogin(name,password);
      }
      return this.instance
  }
}

let obj1 = SingletonLogin.getInstance("zhangsan",'123');
let obj2 = SingletonLogin.getInstance("lisi",'234');

console.log(obj1 === obj2);
console.log(obj1);
console.log(obj2);