Add typing file

index.d.ts

@@ -0,0 +1,67 @@
+// Type definitions for @koa/cors 3.0
+// Project: https://github.com/koajs/cors
+// Definitions by: Xavier Stouder <https://github.com/Xstoudi>
+//                 Izayoi Ko <https://github.com/izayoiko>
+//                 Steve Hipwell <https://github.com/stevehipwell>
+//                 Steven McDowall <https://github.com/sjmcdowall>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.3
+
+import * as Koa from 'koa';
+
+export = cors;
+
+/**
+ * CORS middleware factory.
+ * @param options - Configuration options.
+ * @returns cors middleware
+ */
+declare function cors(options?: cors.Options): Koa.Middleware;
+
+declare namespace cors {
+    /**
+     * Middleware configration options.
+     */
+    interface Options {
+        /**
+         * `Access-Control-Allow-Origin`, default is request Origin header.
+         *
+         * @remarks
+         * If a function is provided, it will be called for each request with
+         * the koa context object. It may return a string or a promise that
+         * will resolve with a string.
+         */
+        origin?: ((ctx: Koa.Context) => string) | ((ctx: Koa.Context) => PromiseLike<string>) | string;
+
+        /**
+         * `Access-Control-Allow-Methods`, default is
+         * 'GET,HEAD,PUT,POST,DELETE,PATCH'
+         */
+        allowMethods?: string[] | string;
+
+        /**
+         * `Access-Control-Expose-Headers`
+         */
+        exposeHeaders?: string[] | string;
+
+        /**
+         * `Access-Control-Allow-Headers`
+         */
+        allowHeaders?: string[] | string;
+
+        /**
+         * `Access-Control-Max-Age` in seconds
+         */
+        maxAge?: number | string;
+
+        /**
+         * `Access-Control-Allow-Credentials`
+         */
+        credentials?: boolean;
+
+        /**
+         * Add set headers to `err.header` if an error is thrown
+         */
+        keepHeadersOnError?: boolean;
+    }
+}

package.json

@@ -3,6 +3,7 @@
   "version": "3.1.0",
   "description": "Cross-Origin Resource Sharing(CORS) for koa",
   "main": "index.js",
+  "typings": "index.d.ts",
   "files": [
     "index.js"
   ],