@felixgeelhaar/glossa-format

@felixgeelhaar/glossa-format

ICU MessageFormat subset — variable interpolation, plurals via Intl.PluralRules, select, nesting, apostrophe escaping. Zero runtime dependencies. ~400 LOC, ~9 KB unpacked.

pnpm add @felixgeelhaar/glossa-format

Usage

import { format, parse } from "@felixgeelhaar/glossa-format";

format("Hello, {name}!", "en", { name: "Sophia" });
// → "Hello, Sophia!"

format(
  "{count, plural, one {# session} other {# sessions}}",
  "en",
  { count: 3 },
);
// → "3 sessions"

format(
  "{gender, select, female {She did it} male {He did it} other {They did it}}",
  "en",
  { gender: "female" },
);
// → "She did it"

For hot paths, parse once and reuse the AST:

const ast = parse("{count, plural, one {# tip} other {# tips}}");
format(ast, "de", { count: 1 }); // → "1 Tipp"

Supported ICU features

Feature	Example
Variable interpolation	{name}
Plural categories	{n, plural, zero{…} one{…} two{…} few{…} many{…} other{…}}
Numeric plural override	{n, plural, =0{none} one{…} other{…}}
Hash placeholder inside plural	{count, plural, one {# item} other {# items}}
Select	{gender, select, female{…} male{…} other{…}}
Nested patterns	plurals inside select inside variable substitution
Apostrophe escaping	it''s → it's, '{literal}' → {literal}

Plural keyword resolution defers to Intl.PluralRules so the package works across the ~100 locales the browser ships without bundling CLDR. Falls back to "other" on environments without Intl.PluralRules.

Out of scope

• Numbers / dates / relative time — use Intl.NumberFormat, Intl.DateTimeFormat, Intl.RelativeTimeFormat directly.
• Custom formatter extension API.
• Bidi / RTL re-ordering.

License

MIT