4 Best Practices for Controllers in AngularJS

1. Keep Controllers Lightweight

Controllers should be focused on managing the view logic and should not contain complex business logic. Complex logic should be delegated to services. This practice ensures that controllers remain easy to test and maintain.

Imagine a controller as a traffic cop directing cars (data) to their correct lanes (views). The cop doesn't need to know how the cars work internally; that's the job of the mechanics (services).

2. Use Dependency Injection

AngularJS provides a powerful dependency injection mechanism. Use it to inject services, factories, and other dependencies into your controllers. This makes your code modular, testable, and easier to manage.

Think of dependency injection as a tool belt for a craftsman. Instead of carrying all tools at once, the craftsman picks the right tool (dependency) when needed, making the job more efficient.

3. Avoid DOM Manipulation

Controllers should not directly manipulate the DOM. Instead, use directives for DOM manipulation. This separation of concerns ensures that your controllers remain focused on logic and data, making your code cleaner and more maintainable.

Consider controllers as chefs preparing ingredients (data), while directives are the kitchen tools (DOM elements) used to cook the meal. The chef doesn't need to know how each tool works; they just need to use them correctly.

4. Limit the Scope of Controllers

Controllers should be limited to the scope of their views. Avoid creating large, monolithic controllers that handle multiple views. Instead, create smaller, focused controllers that handle specific parts of the application.

Think of controllers as specialized doctors in a hospital. Each doctor (controller) handles a specific area (view), ensuring that patients (data) receive the best care possible.