MVC vs MVVM

Mohan Kumar / August 2021

964 Words, 6 Minutes

Understanding Model-View-Controller (MVC) Pattern in Software Development with Examples in Pure JavaScript

Model-View-Controller (MVC) is a widely used architectural pattern in software development that separates the application logic into three main components: Model, View, and Controller. Each component has a specific role and responsibility in the application, promoting a clear separation of concerns and making the code easier to maintain and test.

MVC is commonly used in web development, where the Model represents the data and business logic, the View represents the user interface, and the Controller acts as an intermediary between the Model and the View, handling user input and updating the Model and View accordingly.

Let’s explore the three components of MVC and their roles in a software application, along with examples in pure JavaScript.

1. Model: The Model component in MVC is responsible for managing the data and business logic of the application. It represents the underlying data structure and defines how the data is stored, retrieved, and manipulated.

Example in JavaScript:

class UserModel {
  constructor(username, password) {
    this.username = username;
    this.password = password;
  }

  isValidUser() {
    // Logic to validate user credentials
  }

  getUserData() {
    // Logic to fetch user data from a database
  }

  updateUserData(data) {
    // Logic to update user data in a database
  }
}

1. View: The View component in MVC is responsible for rendering the user interface and displaying the data to the user. It receives updates from the Model and displays the data accordingly. The View should not contain any business logic or modify the data directly.

Example in JavaScript:

class UserView {
  constructor() {
    this.usernameInput = document.getElementById('username');
    this.passwordInput = document.getElementById('password');
    this.loginButton = document.getElementById('login');

    this.loginButton.addEventListener('click', this.handleLoginButtonClick.bind(this));
  }

  renderUserData(userData) {
    // Render user data in the view
  }

  handleLoginButtonClick() {
    const username = this.usernameInput.value;
    const password = this.passwordInput.value;
    // Logic to handle login button click and pass data to the Controller
  }
}

1. Controller: The Controller component in MVC acts as an intermediary between the Model and the View. It receives user input from the View, updates the Model accordingly, and updates the View with the latest data from the Model. The Controller is responsible for handling user interactions, updating the Model, and synchronizing the View.

Example in JavaScript:

class UserController {
  constructor(model, view) {
    this.model = model;
    this.view = view;
  }

  init() {
    // Initialize the controller
    this.view.renderUserData(this.model.getUserData());
  }

  handleLogin(username, password) {
    if (this.model.isValidUser(username, password)) {
      const userData = this.model.getUserData(username);
      this.view.renderUserData(userData);
    } else {
      // Handle invalid credentials
    }
  }

  handleLogout() {
    // Logic to handle user logout and update the View
  }
}

In the above example, the UserController acts as the Controller, UserView acts as the View, and UserModel acts as the Model. The Controller receives user input from the View, updates the Model accordingly, and updates the View with the latest data from the Model.

When Should MVVM vs MVC Be Used ?

The decision to use Model-View-Controller (MVC) or Model-View-ViewModel (MVVM) in software development depends on various factors, such as the specific requirements of the project, the technology stack being used, and the team’s expertise and familiarity with the patterns. Here are some guidelines on when to use MVC or MVVM:

Use MVC when:

1. You want a clear separation of concerns between the Model, View, and Controller components.
2. You have a small to medium-sized project with relatively simple user interface requirements.
3. You are working with technologies that are better suited for the traditional request-response flow, such as server-side web applications or desktop applications.
4. You have a team that is familiar with the MVC pattern and can effectively implement and maintain the separation of concerns.

Example: A server-side web application that uses a backend framework like Express.js for handling HTTP requests, and a frontend framework like Angular.js for rendering views and handling user interactions.

Use MVVM when:

1. You want a separation of concerns between the Model, View, and ViewModel components, with a strong focus on data binding and declarative UI updates.
2. You have complex user interface requirements that involve extensive data binding, two-way data binding, and dynamic updates.
3. You are working with technologies that support data binding and reactive programming, such as modern frontend frameworks like Vue.js, React.js, or Knockout.js.
4. You have a team that is familiar with the MVVM pattern and can effectively implement data binding and reactive programming concepts.

Example: A modern single-page application (SPA) that uses a frontend framework like React.js or Vue.js, with complex user interfaces that require real-time updates and data binding between the View and ViewModel.

In summary, both MVC and MVVM are popular architectural patterns in software development, and the decision to use one over the other depends on the specific requirements of the project, the technology stack being used, and the team’s expertise. MVC is suitable for smaller projects with simpler user interface requirements, while MVVM is ideal for larger projects with complex user interfaces that require extensive data binding and real-time updates. It’s important to carefully consider the pros and cons of each pattern and choose the one that best fits your project’s needs.

Also MVC is a widely used architectural pattern in software development that promotes separation of concerns and improves code maintainability. The Model manages the data and business logic, the View renders the user interface, and the Controller handles user interactions and updates the Model and View accordingly. By understanding the roles of each component and their interactions, developers can create