From 4cd3d1995545cb7377b0ee9005b0592681e34ecd Mon Sep 17 00:00:00 2001
From: Aankhen <Aankhen@users.noreply.github.com>
Date: Fri, 3 Jan 2020 05:08:50 +0530
Subject: [PATCH] koa__cors: Allow `origin` to be a function returning a
 promise. (#41288)

---
 types/koa__cors/index.d.ts         |  4 ++--
 types/koa__cors/koa__cors-tests.ts | 10 +++++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/types/koa__cors/index.d.ts b/types/koa__cors/index.d.ts
index da58136652..8b44fb8a43 100644
--- a/types/koa__cors/index.d.ts
+++ b/types/koa__cors/index.d.ts
@@ -1,4 +1,4 @@
-// Type definitions for @koa/cors 2.2
+// 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>
@@ -15,7 +15,7 @@ declare function cors(options?: cors.Options): Koa.Middleware;
 
 declare namespace cors {
     interface Options {
-        origin?: ((ctx: Koa.Context) => string) | string;
+        origin?: ((ctx: Koa.Context) => string) | ((ctx: Koa.Context) => PromiseLike<string>) | string;
         allowMethods?: string[] | string;
         exposeHeaders?: string[] | string;
         allowHeaders?: string[] | string;
diff --git a/types/koa__cors/koa__cors-tests.ts b/types/koa__cors/koa__cors-tests.ts
index 25f068eb13..0889f7c70d 100644
--- a/types/koa__cors/koa__cors-tests.ts
+++ b/types/koa__cors/koa__cors-tests.ts
@@ -4,10 +4,18 @@ import cors = require('@koa/cors');
 const app = new Koa();
 app.use(cors());
 
-// Trying using cors() passing in a function ..
+// Trying using cors() passing in a function...
 function testCorsFunction(ctx: Koa.Context) {
     const requestOrigin = ctx.request.origin;
     return requestOrigin;
 }
 
 app.use(cors({ origin: testCorsFunction }));
+
+// Trying using cors() passing in a function that returns a promise...
+function testCorsPromiseFunction(ctx: Koa.Context) {
+    const requestOrigin = ctx.request.origin;
+    return Promise.resolve(requestOrigin);
+}
+
+app.use(cors({ origin: testCorsPromiseFunction }));