add typescript type definitions

index.d.ts

@@ -0,0 +1,20 @@
+declare module "iso-639-1" {
+  interface ISO6391 {
+    getName: (code: string) => string;
+    getAllNames: () => Array<string>;
+    getNativeName: (code: string) => string;
+    getAllNativeNames: () => Array<string>;
+    getCode: (name: string) => string;
+    getAllCodes: () => Array<string>;
+    validate: (code: string) => boolean;
+    getLanguages: (codes: Array<string>) => Array<{
+      code: string;
+      name: string;
+      nativeName: string;
+    }>;
+  }
+
+  let localeCode: ISO6391;
+
+  export = localeCode;
+}

package.json

@@ -3,6 +3,7 @@
   "version": "2.0.1",
   "description": "ISO-639-1 codes",
   "main": "build/index.js",
+  "typings": "index.d.ts",
   "scripts": {
     "build": "babel src --out-dir build",
     "test": "mocha"