icu2ts

icu2ts

Generate type definitions for ICU messages. This is meant as a building block for typesafe i18n libraries.

Example

import { generateType } from "icu2ts";

const message =
    "Hello {name}! You have {count, plural, one {1 message} other {# messages}}.";

const typeDefinition = generateType(message);

// typeDefinition = { name: string, count: number };

The types may not be as compact as they could be, but they are correct.

Caveats

When a select, plural, or selectordinal with an "other" branch is encountered it is not possible to use a type-union, since the fallback type would match all branches, not just the fallback. Instead, the type is a union of all branch-types. This is rarely a problem, but you should be aware of it.

Eg:

const msg = "{count, plural, one {1 {arg1}} other {# {arg2}}}";
//becomes
{ count: number } & ({ arg1: string } | { arg2: string }); //No type-narrowing

Until TypeScript supports a union of the form "a" | string, this is the best we can do.