formatting.md

Message syntax

There are roughly two ways to describe messages:

• JavaScript DSL uses JavaScript functions to build type-safe messages.
• MessageFormat syntax uses a dedicated syntax for translation structures.

JavaScript DSL

To write translations in JavaScript DSL, use various helpers from @hi18n/core/msg.

import { Catalog, type Message } from "@hi18n/core";
import { msg, arg } from "@hi18n/core/msg";

type Vocabulary = {
  "root/greeting": Message<{ name: string }>;
};

const catalogEn = new Catalog<Vocabulary>("en", {
  "root/greeting": msg`Hello, ${arg("name")}!`,
});

MessageFormat syntax

To write translations in MessageFormat syntax, use the mf1 helper from @hi18n/core/msg.

import { Catalog, type Message } from "@hi18n/core";
import { mf1 } from "@hi18n/core/msg";

type Vocabulary = {
  "root/greeting": Message<{ name: string }>;
};

const catalogEn = new Catalog<Vocabulary>("en", {
  "root/greeting": mf1("Hello, {name}!"),
});

There is also a msg helper from @hi18n/core for backward compatibility, but @hi18n/core/msg is preferred.

// msg is deprecated. Use mf1.
import { Catalog, type Message, msg } from "@hi18n/core";

type Vocabulary = {
  "root/greeting": Message<{ name: string }>;
};

const catalogEn = new Catalog<Vocabulary>("en", {
  "root/greeting": msg("Hello, {name}!"),
});

For syntax structures used within the function, see Message syntax (MessageFormat 1.0).