Lab 24: Internationalization (i18n)

📖 Resources

• i18n Reference

🚀 Starter Code

album-wholesale-v17-signal-pre-jest

In this lab you will add multi-language support to the album wholesale app using Angular’s built-in i18n system. You will mark strings for translation, extract an XLIFF message file, provide a French translation, and build a localized bundle.

📝 Instructions

Step 1: Mark Strings in Templates

Add the i18n attribute to text elements:

<!-- Simple text -->
<h1 i18n="@@app.title">Album Store</h1>

<!-- With description for translators -->
<p i18n="Album count|Shows the number of albums@@album.count">
  Available albums
</p>

<!-- Attribute translation -->
<input
  type="search"
  i18n-placeholder="@@search.placeholder"
  placeholder="Search albums…"
/>

<!-- Button -->
<button i18n="@@cart.add">Add to cart</button>

Mark at least 5 strings across the app.

Step 2: Configure the Source Locale

In angular.json, add i18n configuration:

{
  "projects": {
    "album-wholesale": {
      "i18n": {
        "sourceLocale": "en-US",
        "locales": {
          "fr": {
            "translation": "src/locale/messages.fr.xlf"
          }
        }
      }
    }
  }
}

Step 3: Extract the Message File

ng extract-i18n --format xlf2 --output-path src/locale

This generates src/locale/messages.xlf. Open the file — you will see each marked string as a <trans-unit>.

Step 4: Create the French Translation

Copy the source file and rename it:

cp src/locale/messages.xlf src/locale/messages.fr.xlf

Open messages.fr.xlf and add <target> elements for each unit:

<trans-unit id="app.title" datatype="html">
  <source>Album Store</source>
  <target>Boutique d'Albums</target>
</trans-unit>

<trans-unit id="cart.add" datatype="html">
  <source>Add to cart</source>
  <target>Ajouter au panier</target>
</trans-unit>

<trans-unit id="search.placeholder" datatype="html">
  <source>Search albums…</source>
  <target>Rechercher des albums…</target>
</trans-unit>

Translate all extracted units.

Step 5: Use Plural and Select Expressions

<!-- Plural -->
<p i18n="@@cart.items">
  {itemCount, plural,
    =0 {No items in cart}
    =1 {1 item in cart}
    other {{{itemCount}} items in cart}
  }
</p>

<!-- Select (gender or category) -->
<span i18n="@@album.type">
  {albumType, select,
    vinyl {Vinyl record}
    cd {Compact disc}
    other {Digital}
  }
</span>

Add French translations for these expressions in messages.fr.xlf:

<trans-unit id="cart.items" datatype="html">
  <source>
    {itemCount, plural,
      =0 {No items in cart}
      =1 {1 item in cart}
      other {{{itemCount}} items in cart}
    }
  </source>
  <target>
    {itemCount, plural,
      =0 {Aucun article}
      =1 {1 article}
      other {{{itemCount}} articles}
    }
  </target>
</trans-unit>

Step 6: Build with Localization

Configure the build target in angular.json:

"build": {
  "configurations": {
    "fr": {
      "localize": ["fr"]
    },
    "production": {
      "localize": true
    }
  }
}

Build all locales:

ng build --localize

Inspect the dist/ folder — you should see browser/en-US/ and browser/fr/ subdirectories.

Step 7: Serve and Verify

Serve the French build locally:

cd dist/album-wholesale/browser/fr
npx http-server -p 8080

Open http://localhost:8080 and verify all marked strings appear in French.