feat!: Type-safe ICU arguments

[amannn]

{
  "UserProfile": {
    "title": "Hello {firstName}"
  }
}

function UserProfile({user}) {
  const t = useTranslations('UserProfile');
 
  // ✖️ Missing argument
  t('title');
 
  // ✅ Argument is provided
  t('title', {firstName: user.firstName});
}

Features

• ICU arguments can now be validated with TypeScript (however, currently this is opt-in)

Breaking changes

• undefined and null are no longer accepted as values for calls to t.

→ Proposed docs

---

Performance notes from a sample project

Scope:

• 342 messages in total
• 290 plain messages
• 14 messages with simple params
• 1 message with plural
• 9 messages with date formatting
• 20 messages with select
• 8 messages with rich text

Check time from tsc --diagnostics:

• No type augmentation for messages: ~2.20s
• Type-safe keys: ~2.82s
• Type-safe arguments: ~2.85s

This was observed on a MacBook Pro 2019 (Intel).

---

Resolves #410

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
next-intl-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 7, 2024 2:23pm
next-intl-example-app-router	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 7, 2024 2:23pm
next-intl-example-app-router-without-i18n-routing	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Nov 7, 2024 2:23pm