Dual packaging, without breaking existing consumers (#628)

Co-authored-by: Yasumasa Ashida <ys.ashida@gmail.com>

index.d.mts

@@ -0,0 +1,33 @@
+// ESM type definitions for Bowser v2.
+//
+// `index.d.ts` uses `export =`, which describes the CommonJS/UMD shape of
+// `es5.js` (`module.exports = Bowser`). It is reached via the `require`
+// condition and stays the source of truth for the type declarations.
+//
+// This file describes `bowser.mjs`, which is a real ES module: it has a default
+// export *and* the `parse` / `getParser` named exports. It is reached via the
+// `import` condition. Declaring it separately is what keeps the types honest
+// for `moduleResolution: node16`/`bundler` consumers — reusing `index.d.ts` for
+// both conditions would describe an ES module with CommonJS types.
+
+import Bowser = require('./index.js');
+
+export default Bowser;
+
+export declare const parse: typeof Bowser.parse;
+export declare const getParser: typeof Bowser.getParser;
+
+// BROWSER_MAP / ENGINE_MAP / OS_MAP / PLATFORMS_MAP are *not* named exports of
+// bowser.mjs — they exist only as static getters on the class. Declaring them
+// here would let TypeScript accept `import { BROWSER_MAP } from 'bowser'`,
+// which throws at runtime. Reach them via the default export instead.
+
+export type ClientHints = Bowser.ClientHints;
+export type Parser = Bowser.Parser.Parser;
+export type ParsedResult = Bowser.Parser.ParsedResult;
+export type Details = Bowser.Parser.Details;
+export type BrowserDetails = Bowser.Parser.BrowserDetails;
+export type EngineDetails = Bowser.Parser.EngineDetails;
+export type OSDetails = Bowser.Parser.OSDetails;
+export type PlatformDetails = Bowser.Parser.PlatformDetails;
+export type checkTree = Bowser.Parser.checkTree;