React native- Best way to create singleton pattern

You can use something like that

 class SingletonClass {

  static instance = null;
  static createInstance() {
      var object = new SingletonClass();
      return object;
  }

  static getInstance () {
      if (!SingletonClass.instance) {
          SingletonClass.instance = SingletonClass.createInstance();
      }
      return SingletonClass.instance;
  }
}

var instance1 = SingletonClass.getInstance();
var instance2 = SingletonClass.getInstance();

Here's my implementation for singleton class...

Controller.js

export default class Controller {
    static instance = Controller.instance || new Controller()

    helloWorld() {
        console.log("Hello World... \(^_^)/ !!")
    }
}

Usage:

import Controller from 'Controller.js'

Controller.instance.helloWorld()