Why standalone components matter in Angular - See It in Action

Why standalone components matter

📋 What You'll Learn

💡 Why This Matters

🌍 Real World

Standalone components simplify Angular app structure, making it easier to build and maintain small to medium apps or micro frontends.

💼 Career

Understanding standalone components is important for modern Angular development and helps you write cleaner, more efficient code that aligns with the latest Angular best practices.

1

Create the standalone component

Create a standalone Angular component named WelcomeComponent with the selector app-welcome. Use the @Component decorator with standalone: true and a template that contains an <h1> tag with the text 'Welcome to Angular Standalone Components!'.

Angular

import { Component } from '@angular/core';

// Your code here

Hint

Use the @Component decorator with the standalone: true option and define the template inline.

2

Bootstrap the standalone component

In the main.ts file, bootstrap the WelcomeComponent directly using bootstrapApplication from @angular/platform-browser. Import bootstrapApplication and WelcomeComponent and call bootstrapApplication(WelcomeComponent).

Angular

import { bootstrapApplication } from '@angular/platform-browser';
import { WelcomeComponent } from './app/welcome.component';

// Your code here

Hint

Use bootstrapApplication to start the app with the standalone component.

3

Add styles to the component

Add a styles array to the @Component decorator in WelcomeComponent with a CSS rule that sets the h1 color to navy.

Angular

import { Component } from '@angular/core';

@Component({
  selector: 'app-welcome',
  standalone: true,
  template: `Welcome to Angular Standalone Components!`,
  // Your code here
})
export class WelcomeComponent {}

import { bootstrapApplication } from '@angular/platform-browser';
import { WelcomeComponent } from './app/welcome.component';

bootstrapApplication(WelcomeComponent);

Hint

Add a styles property with an array of CSS strings inside the @Component decorator.

4

Add accessibility with ARIA label

Add an aria-label attribute with the value 'Welcome message' to the <h1> tag in the WelcomeComponent template.

Angular

import { Component } from '@angular/core';

@Component({
  selector: 'app-welcome',
  standalone: true,
  template: `Welcome to Angular Standalone Components!`,
  styles: [
    `h1 { color: navy; }`
  ]
})
export class WelcomeComponent {}

import { bootstrapApplication } from '@angular/platform-browser';
import { WelcomeComponent } from './app/welcome.component';

bootstrapApplication(WelcomeComponent);

Hint

Add the aria-label attribute inside the <h1> tag in the template string.

Practice

1. What is the main benefit of using standalone: true in an Angular component?

easy

A. It allows the component to work without needing an NgModule.

B. It makes the component run faster in the browser.

C. It automatically adds routing to the component.

D. It converts the component into a service.

Solution

1. Step 1: Understand the role of NgModules

   NgModules group components, but standalone components remove this need.

2. Step 2: Identify what standalone: true does

   This flag makes the component independent, so it doesn't require an NgModule.

3. Final Answer:

   It allows the component to work without needing an NgModule. -> Option A

4. Quick Check:

   Standalone components = no NgModule needed [OK]

Hint: Standalone means no NgModule needed for the component [OK]

Common Mistakes:

• Thinking standalone makes components faster
• Confusing standalone with routing features
• Believing standalone converts components to services

2. Which of the following is the correct way to declare a standalone component in Angular?

easy

A. @NgModule({ standalone: true }) export class ExampleComponent {}

B. @Component({ selector: 'app-example', module: true }) export class ExampleComponent {}

C. @Component({ selector: 'app-example', standalone: true }) export class ExampleComponent {}

D. @Component({ selector: 'app-example' }) export class ExampleComponent {}

Solution

1. Step 1: Recall the syntax for standalone components

   Standalone components use standalone: true inside the @Component decorator.

2. Step 2: Check each option's syntax

   @Component({ selector: 'app-example', standalone: true }) export class ExampleComponent {} correctly uses @Component with standalone: true. Others misuse decorators or omit the flag.

3. Final Answer:

   @Component({ selector: 'app-example', standalone: true }) export class ExampleComponent {} -> Option C

4. Quick Check:

   Standalone flag inside @Component = correct syntax [OK]

Hint: Look for standalone: true inside @Component decorator [OK]

Common Mistakes:

• Using @NgModule instead of @Component
• Writing 'module: true' instead of 'standalone: true'
• Omitting the standalone flag

3. Given this code, what will be the output when AppComponent is rendered?

@Component({ selector: 'app-root', standalone: true, template: `
Hello
`, imports: [ChildComponent] }) export class AppComponent {}
@Component({ selector: 'app-child', standalone: true, template: `
Child works!
` }) export class ChildComponent {}

medium

A. HelloChild works!

B. Hello

C. Error: ChildComponent not declared in NgModule

D. Child works!

Solution

1. Step 1: Check how ChildComponent is included

   AppComponent imports ChildComponent in its imports array, allowing usage in its template.

2. Step 2: Understand standalone component rendering

   Both components are standalone, so ChildComponent renders inside AppComponent's template.

3. Final Answer:

   <h1>Hello</h1><p>Child works!</p> -> Option A

4. Quick Check:

   Standalone imports enable nested component rendering [OK]

Hint: Standalone components must be imported to use in templates [OK]

Common Mistakes:

• Assuming child renders without importing
• Expecting NgModule declaration errors
• Ignoring standalone imports array

4. What is wrong with this standalone component code?

@Component({ selector: 'app-error', standalone: true, template: `
Error component
` }) export class ErrorComponent {}
@Component({ selector: 'app-root', standalone: true, template: ``, imports: [ErrorComponent] }) export class AppComponent {}

medium

A. Standalone components cannot have templates.

B. AppComponent does not import ErrorComponent in its imports array.

C. The selector 'app-error' is invalid for standalone components.

D. ErrorComponent should not be standalone if used inside another component.

Solution

1. Step 1: Check component imports for nested usage

   AppComponent uses <app-error> but does not import ErrorComponent in its imports array.

2. Step 2: Understand standalone component import rules

   Standalone components must import other standalone components they use in templates.

3. Final Answer:

   AppComponent does not import ErrorComponent in its imports array. -> Option B

4. Quick Check:

   Missing import of nested standalone component causes error [OK]

Hint: Always import standalone components you use inside templates [OK]

Common Mistakes:

• Thinking standalone components don't need imports
• Believing selectors are restricted for standalone
• Assuming standalone components can't have templates

5. You want to create a reusable button component as standalone and use it in multiple other standalone components without NgModules. Which approach is correct?

hard

A. Create the button without standalone and declare it in a shared NgModule imported everywhere.

B. Create the button as a directive and add it to the root NgModule.

C. Create the button as a service and inject it into components.

D. Create the button with standalone: true and import it in each component's imports array where used.

Solution

1. Step 1: Understand standalone component reuse

   Standalone components can be reused by importing them directly in other standalone components.

2. Step 2: Identify the correct reuse method without NgModules

   Create the button with standalone: true and import it in each component's imports array where used. uses standalone: true and imports the button in each component, avoiding NgModules.

3. Final Answer:

   Create the button with standalone: true and import it in each component's imports array where used. -> Option D

4. Quick Check:

   Standalone reuse = import in each component [OK]

Hint: Import standalone components where needed; no NgModules required [OK]

Common Mistakes:

• Trying to use NgModules with standalone components
• Confusing services with UI components
• Using directives instead of components for buttons