How Can I Implement a Simple and Clean Singleton Pattern in JavaScript?

Singleton Pattern in JavaScript: Achieving Simplicity and Cleanliness

In JavaScript, implementing the singleton pattern can be achieved in various ways, but what stands out is the pursuit of simplicity and cleanliness. One approach that embodies these qualities is the straightforward creation of an object literal, as seen below:

var myInstance = {
  method1: function () {},
  method2: function () {}
};

This method establishes a public interface through the object literal, making its members accessible to other parts of the code.

However, if private members are desired, the module pattern emerges as a popular solution:

var myInstance = (function() {
  var privateVar = '';

  function privateMethod () {}

  return { // public interface
    publicMethod1: function () {},
    publicMethod2: function () {}
  };
})();

The module pattern leverages closures to encapsulate private members within the singleton instance.

To prevent modifications and ensure immutability, the ES5 Object.freeze method can be utilized:

Object.freeze(myInstance);

This action guarantees that any alterations to the singleton object's structure or values are rejected.

In ES6, ES Modules provide an elegant solution for creating singletons:

// my-singleton.js
const somePrivateState = []

function privateFn () {}

export default {
  method1() {},
  method2() {}
}

The module scope conveniently houses both public methods and private variables. Importing the singleton into other modules remains a simple task:

import myInstance from './my-singleton.js'

By adopting these approaches, you empower your JavaScript code with the versatility and simplicity of the singleton pattern, enabling the controlled access and management of shared resources.

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