Translate bot messages with Lang

Configure message dictionaries and let each bot user choose a language with the Lang library.

Install Lang to store message dictionaries and a language choice for each bot user. It does not translate text automatically. Supply the translations you want the bot to send.

1

Configure two languages

Run this once from an owner-only setup command:

Configure two languages · Example 1

Libs.Lang.setup("en", {
  greeting: "Hello!",
  account: { empty: "No saved details yet." }
});
Libs.Lang.setup("es", {
  greeting: "¡Hola!",
  account: { empty: "Todavía no hay datos guardados." }
});
Libs.Lang.default.setLang("en");

The first configured language becomes the default unless you explicitly change it. Re-running setup replaces the dictionary stored under that language name, so include all its keys.

In /hello:

Configure two languages · Example 2

Bot.sendMessage(Libs.Lang.t("greeting"));
Bot.sendMessage(Libs.Lang.t("account.empty"));

Keys such as account.empty are paths in your own dictionary. Keep them fixed in your code; do not pass arbitrary user text as a translation expression.

2

Let a user choose

In /english:

Let a user choose · Example 3

Libs.Lang.user.setLang("en");
Bot.sendMessage(Libs.Lang.t("greeting"));

In /spanish, use Libs.Lang.user.setLang("es"). Configure the dictionary before letting users select it. A selected language with no configured dictionary raises an error.

Reference

Call	Result
Libs.Lang.user.getCurLang()	User's selected language, or default
Libs.Lang.default.getCurLang()	Bot's default language
Libs.Lang.get("en")	Full dictionary for that language
Libs.Lang.t("key", "en")	Translation in an explicitly selected language
Libs.Lang.getCommandByAlias(text, language)	Matching command name from an aliases dictionary

t() falls back to the default language for a missing or falsy value. Use nonempty message strings; an empty string, false or numeric zero is not a reliable translation value for this fallback behavior.

An aliases dictionary can map visible labels to commands:

Reference · Example 4

Libs.Lang.setup("en", {
  greeting: "Hello!",
  aliases: { "Help, Support": "/help" }
});

getCommandByAlias performs a case insensitive lookup. It returns a name; your code decides whether to run it. Translation keys and BJS method names stay unchanged across languages.

If you need whole reply layouts with buttons and placeholders, use SmartBot templates. Its language storage is separate from Libs.Lang.