Angular i18n built-in support - Mini Project: Build & Apply

Angular i18n built-in support

📖 Scenario: You are building a simple Angular app that greets users in different languages. You want to use Angular's built-in i18n support to show the greeting message in English and Spanish.

🎯 Goal: Create an Angular standalone component that uses Angular i18n built-in support to display a greeting message. The message should be marked for translation using Angular's i18n attribute.

📋 What You'll Learn

Create a standalone Angular component named GreetingComponent

Add a heading element with the text Hello, welcome to our site!

Use Angular's i18n attribute on the heading to mark it for translation

Configure the component as standalone with the standalone: true flag

💡 Why This Matters

🌍 Real World

Many websites and apps need to support multiple languages to reach a wider audience. Angular's built-in i18n support helps developers mark text for translation and manage multiple languages easily.

💼 Career

Understanding Angular i18n is important for frontend developers working on internationalized applications, improving user experience for global users.

1

Create the GreetingComponent standalone component

Create a standalone Angular component named GreetingComponent with a template containing an h1 element that displays the text Hello, welcome to our site!.

Angular

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

@Component({
  selector: 'app-greeting',
  template: `
    Hello, welcome to our site!
  `,
  standalone: true
})
export class GreetingComponent {
  // Your code here
}

Hint

Use @Component decorator with standalone: true and define the template with the greeting text inside an h1 tag.

2

Add Angular i18n attribute to the greeting message

Add the Angular i18n attribute to the h1 element in the GreetingComponent template to mark the greeting message for translation.

Angular

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

@Component({
  selector: 'app-greeting',
  template: `
    Hello, welcome to our site!
  `,
  standalone: true
})
export class GreetingComponent {}

// Add the i18n attribute to the h1 element

Hint

Add i18n inside the opening h1 tag to mark the text for translation.

3

Add a language selector variable

Inside the GreetingComponent class, create a public variable named currentLang and set it to the string 'en' to represent the current language.

Angular

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

@Component({
  selector: 'app-greeting',
  template: `
    Hello, welcome to our site!
  `,
  standalone: true
})
export class GreetingComponent {
  currentLang = 'en'; // Your code here
}

Hint

Declare a public variable currentLang inside the class and assign it the string 'en'.

4

Add a language toggle method

Add a public method named toggleLanguage() inside the GreetingComponent class that switches currentLang between 'en' and 'es' when called.

Angular

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

@Component({
  selector: 'app-greeting',
  template: `
    Hello, welcome to our site!
  `,
  standalone: true
})
export class GreetingComponent {
  currentLang = 'en';

  toggleLanguage() {
    // Your code here
  }
}

Hint

Use a ternary operator inside toggleLanguage() to switch currentLang between 'en' and 'es'.

Practice

1. What is the primary purpose of the i18n attribute in Angular templates?

easy

A. To mark text for translation into different languages

B. To apply CSS styles conditionally

C. To bind data to the component

D. To define event handlers for user actions

Solution

1. Step 1: Understand the role of i18n in Angular

   The i18n attribute is used to identify text in templates that should be translated for internationalization.

2. Step 2: Compare with other options

   The other options relate to styling, data binding, and events, which are unrelated to translation.

3. Final Answer:

   To mark text for translation into different languages -> Option A

4. Quick Check:

   i18n attribute = mark text for translation [OK]

Hint: Remember: i18n means internationalization, so it marks text for translation [OK]

Common Mistakes:

• Confusing i18n with data binding syntax
• Thinking i18n applies styles or events
• Assuming i18n is a directive instead of an attribute

2. Which of the following is the correct syntax to mark a paragraph for translation in Angular?

easy

A. Hello, welcome!

B. Hello, welcome!

C. Hello, welcome!

D. Hello, welcome!

Solution

1. Step 1: Recall Angular i18n attribute usage

   The i18n attribute is added directly to the element without brackets or asterisk.

2. Step 2: Analyze each option

   Hello, welcome!

   uses i18n correctly.

   Hello, welcome!

   uses property binding syntax which is incorrect.

   Hello, welcome!

   uses structural directive syntax which is invalid here.

   Hello, welcome!

   uses a non-existent attribute i18n-text.

3. Final Answer:

   <p i18n>Hello, welcome!</p> -> Option D

4. Quick Check:

   Use plain i18n attribute without brackets or asterisk [OK]

Hint: Use plain i18n attribute on elements, no brackets or asterisks [OK]

Common Mistakes:

• Using property binding syntax [i18n]
• Using structural directive syntax *i18n
• Inventing attributes like i18n-text

3. Given this Angular template snippet:

<h1 i18n>Welcome, {{ userName }}!</h1>

What will be the output if userName is 'Alice' and the app is built with English locale?

medium

A. Welcome, !

B. Welcome, {{ userName }}!

C. Welcome, Alice!

D. Error: Missing translation

Solution

1. Step 1: Understand interpolation with i18n

   The i18n attribute marks the text for translation but Angular still processes interpolation expressions like {{ userName }}.

2. Step 2: Consider the locale and variable value

   With English locale and userName as 'Alice', the text renders with the variable replaced by 'Alice'.

3. Final Answer:

   Welcome, Alice! -> Option C

4. Quick Check:

   i18n with interpolation outputs translated text with variables replaced [OK]

Hint: i18n marks text, interpolation fills variables at runtime [OK]

Common Mistakes:

• Thinking interpolation is ignored inside i18n
• Expecting raw {{ userName }} to show
• Assuming missing translation error for default locale

4. You run ng extract-i18n but the generated translation file is empty. What is the most likely cause?

medium

A. The Angular CLI version is outdated

B. No i18n attributes found in templates

C. The app has no components

D. The translation file path is incorrect

Solution

1. Step 1: Understand what ng extract-i18n does

   This command extracts marked text with i18n attributes from templates into translation files.

2. Step 2: Analyze why the file might be empty

   If no i18n attributes exist, there is nothing to extract, resulting in an empty file.

3. Final Answer:

   No i18n attributes found in templates -> Option B

4. Quick Check:

   Empty extraction file means no i18n markers found [OK]

Hint: Check templates for i18n attributes before extracting [OK]

Common Mistakes:

• Assuming CLI version causes empty file
• Thinking app components absence causes empty file
• Confusing file path issues with extraction content

5. You want to build your Angular app to support English and French using built-in i18n. Which steps are required to serve users in their language?

hard

A. Extract translations, provide French translation file, build app twice with different locales

B. Add i18n attribute, write translations inline, build once

C. Use runtime translation service only, no build changes needed

D. Create separate components for each language manually

Solution

1. Step 1: Extract translations and provide translation files

   Use Angular CLI to extract text marked with i18n and create translation files for English and French.

2. Step 2: Build the app separately for each locale

   Build the app twice, once with English locale and once with French locale, so each build contains the correct translations.

3. Final Answer:

   Extract translations, provide French translation file, build app twice with different locales -> Option A

4. Quick Check:

   Angular i18n requires extraction, translation files, and separate builds [OK]

Hint: Extract, translate, build per locale to support multiple languages [OK]

Common Mistakes:

• Thinking inline translations replace translation files
• Assuming runtime service handles built-in i18n translations
• Trying to create separate components per language manually