Breaking Down Your Angular Application: Why and How to Create New Components

  • Angular 19
  • Router

As your Angular app grows, organizing code into smaller components can make a big difference in readability, maintainability, and reusability. In this post, we’ll explore why isolating parts of your app into new components can benefit your project, how to decide where to put them, and the different roles these components can play. Whether you’re just starting with Angular or looking to structure your projects better, this guide will help you understand the basics of component organization.

Why Create New Components?

When you’re just beginning with Angular, it’s tempting to put all of your code into a single component because it seems easier. It might be fine for a simple app though, as Stephen Fluin explains in his Single Component Angular Apps blog post. However, as your app gets more complex, this approach can lead to a tangled mess that’s hard to work with. Here’s why breaking down your app into smaller components is a smart move:

1. Separation of Concerns

Every component should have a single responsibility. When one component handles too many things—like data fetching, complex UI interactions, and business logic—it becomes difficult to understand and maintain. Creating smaller components with specific responsibilities makes it easier to manage each part of your app independently.

Example: Instead of a “UserProfile” component that handles fetching data, editing, and displaying the user’s profile, you could break it down into:

  • UserProfile: Fetches the user data and manages state.
  • UserProfileDisplay: Displays the user information.
  • UserProfileEdit: Handles the editing functionality.

2. Code Readability

Imagine a component with hundreds of lines of HTML, CSS, and TypeScript code. It becomes hard to read and understand, even if you’re the one who wrote it. By splitting parts of a big component into smaller ones, you make each one easier to read. Smaller, well-named components can describe their purpose just by their name, which also makes it easier for other team members (or future you) to navigate the code.

3. Reusability

Sometimes you write code that would be helpful in other parts of your app. If you keep that code in one big component, you’ll end up duplicating it when you need it elsewhere. By isolating common functionality into separate components, you can reuse them anywhere in your app.

Example: A button styled a certain way or a form field could be placed in a shared component so you can use it across multiple pages or features without rewriting it.

Where to Create New Components?

When you’re ready to create a new component, think about where it should live in your project structure. Angular’s module system is great for organizing components, and here are a few tips to help you decide where to place them:

1. Component Hierarchy

If the new component is only relevant to a particular feature, place it within the folder for that feature. This keeps things organized and shows its relation to other parts of the app. Often, components that are closely related sit together within a parent-child structure.

Example: If you’re building a dashboard with a “Statistics” component, you might break out “UserStats” and “ProductStats” as children components within the dashboard folder.

2. Feature Modules

Grouping components within feature modules is a good practice, especially when these components are only used within a particular feature. Feature modules keep the application modular and allow for lazy loading, which means only loading what the user needs when they need it.

Example: Place all components related to “User Management” in a user-management feature module. This keeps it organized and allows you to load the module only when the user accesses that part of the app.

3. Shared Modules

For components that you’ll need across multiple parts of the app, such as buttons, alerts, or form inputs, use a shared module. This module can hold reusable UI elements and utility components, keeping your code DRY (Don’t Repeat Yourself).

What Are the Different Roles of Components?

Components can have different roles in your application, each with its own purpose and best practices. Here’s a breakdown of common component types you might use in an Angular app:

1. Container Components

These components handle data-fetching and state management, acting as a middleman between services and presentation components. They don’t focus on UI details but rather on managing data.

Example: A “UserProfile” container component could fetch the user’s profile data and pass it down to “UserProfileDisplay” and “UserProfileEdit” components.

2. Presentational Components

These are UI-focused components. They display data but don’t handle any state or business logic themselves. They receive data via @Input() properties and emit events to the parent component using @Output().

Example: The “UserProfileDisplay” component mentioned earlier is a presentational component that simply displays data passed to it.

3. UI Components

Small, reusable components like buttons, form fields, or icons fall into this category. These components are often simple, handling only UI rendering, and are usually part of a shared module.

Example: A “CustomButton” component that you can style once and reuse throughout the app whenever a button is needed.

4. Smart vs. Dumb Components

“Smart” components manage data and handle business logic, while “dumb” components (also called “pure” or “presentational” components) only focus on displaying data. Keeping most components as “dumb” makes them more reusable and easier to test.

5. Routing Components

These components are created specifically for pages or sections that the user can navigate to. They often act as containers for other components and are responsible for configuring routes and handling navigation within a feature.

Example: If you have a “Profile” route, you might create a ProfileComponent that loads the user’s information and displays child components like “UserInfo” and “UserSettings.”

Final Thoughts

Creating new components might feel like extra work at first, but breaking down your app into smaller, purpose-driven parts makes it easier to understand, maintain, and extend. By carefully choosing where to create these components and keeping their roles clear, you’ll find that your Angular app becomes easier to work with as it grows. The practice of dividing responsibilities also makes testing simpler, since each component has a clear purpose and predictable behavior.

Start small, try breaking down one of your bigger components, and see how it changes the way you work with your code!