AI solution for Interview Question on BFE.dev
116. What is Singleton Pattern?

Singleton Pattern is a design pattern that restricts the instantiation of a class to a single instance and ensures that the instance is globally accessible. It is a Creational Pattern that allows us to create only one instance of a class and provide a global point of access to it.

In JavaScript, we can implement Singleton Pattern using an object literal or an Immediately Invoked Function Expression (IIFE). The key idea is to create a single instance of an object and return that instance every time the Singleton is requested.

For example, here is a simple implementation of a Singleton using an object literal:

const mySingleton = {
  prop1: 'value',
  prop2: 'value',
  method1: function() {
    console.log('method 1');
  }
};

// Access the Singleton instance
mySingleton.method1();
console.log(mySingleton.prop1);

This implementation creates a single object (mySingleton) that contains some properties and methods. Whenever we want to access the Singleton instance, we simply refer to mySingleton.

Overall, Singleton Pattern is useful when we want to ensure that only one instance of a class is created, such as when we are working with resource-intensive objects like databases or network connections.