Singleton Pattern in JavaScript Easy Guide!

In this article, you will learn about Singleton Pattern in JavaScript.

There is only one instance of a class and no way to create additional instances of the same class in Singleton Pattern in JavaScript. Singleton objects are typically used in applications to manage global state.

let firebaseInstance = null;
export const getFirebase = () => {
  if (firebaseInstance !== null) {
    return firebaseIntance;
  }

  firebase.initializeApp(config);
  firebaseInstance = firebase;
  return firebaseInstance;
};

Using ES6 Classes

let singletonInstance = null;
class Singleton {
  constructor() {
    if (!singletonInstance) {
      singletonInstance = this;
      console.log('Instance created');
    }
    return singletonInstance;
  }
}
const singletonObject = new Singleton();

Using ES7 Classes

class Singleton {
  static singletonInstance = null;
  static getSingletonInstance() {
    if (!Singleton.singletonInstance) {
      Singleton.singletonInstance = new Singleton();
      console.log('Instance created');
    }
    return Singleton.singletonInstance;
  }
}
const singletonObject = Singleton.getSingletonInstance();

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