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Module Pattern Use Cases

Module Pattern Use Cases

Introduction

The Module pattern is best suited for scenarios where you need encapsulation, namespace management, or controlled access to internal state.

Singleton Services

const Config = (function() {
  const config = {
    apiUrl: 'https://api.example.com',
    timeout: 5000,
    retries: 3
  };

  return {
    get(key) { return config[key]; },
    set(key, value) { config[key] = value; },
    getAll() { return { ...config }; }
  };
})();

Namespace Management

// Before modules — prevent global namespace pollution
const MyApp = (function() {
  // All internal code is scoped here

  const Utils = {
    formatDate(date) { /* ... */ },
    debounce(fn, ms) { /* ... */ }
  };

  const API = {
    async get(url) { /* ... */ },
    async post(url, data) { /* ... */ }
  };

  return { Utils, API };
})();

MyApp.API.get('/users');

Counter / State Management

const Counter = (function() {
  let count = 0;

  return {
    increment() { return ++count; },
    decrement() { return --count; },
    reset() { count = 0; },
    getCount() { return count; }
  };
})();

Summary

Singleton services (config, logging)
Namespace management (avoid global pollution)
Simple state management without a framework
Legacy codebases (pre-ES modules)

Further Reading

MDN: JavaScript Modules