feat(types): support contextual typing from server

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## next
 
+- feat(typescript): type improvements ([#882](https://github.com/chimurai/http-proxy-middleware/pull/882))
 - chore(deps): update micromatch to 4.0.5
 - chore(package): bump devDependencies
 - feat(legacyCreateProxyMiddleware): show migration tips ([#756](https://github.com/chimurai/http-proxy-middleware/pull/756))

package.json

@@ -83,7 +83,7 @@
     "ws": "8.10.0"
   },
   "dependencies": {
-    "@types/http-proxy": "^1.17.9",
+    "@types/http-proxy": "^1.17.10",
     "debug": "^4.3.4",
     "http-proxy": "^1.18.1",
     "is-glob": "^4.0.1",

src/http-proxy-middleware.ts

@@ -14,7 +14,7 @@ export class HttpProxyMiddleware<TReq, TRes> {
   private wsInternalSubscribed = false;
   private serverOnCloseSubscribed = false;
   private proxyOptions: Options<TReq, TRes>;
-  private proxy: httpProxy;
+  private proxy: httpProxy<TReq, TRes>;
   private pathRewriter;
 
   constructor(options: Options<TReq, TRes>) {
@@ -75,7 +75,7 @@ export class HttpProxyMiddleware<TReq, TRes> {
     }
   };
 
-  private registerPlugins(proxy: httpProxy, options: Options<TReq, TRes>) {
+  private registerPlugins(proxy: httpProxy<TReq, TRes>, options: Options<TReq, TRes>) {
     const plugins = getPlugins<TReq, TRes>(options);
     plugins.forEach((plugin) => {
       debug(`register plugin: "${getFunctionName(plugin)}"`);

src/types.ts

@@ -26,7 +26,7 @@ export type Filter<TReq = http.IncomingMessage> =
   | ((pathname: string, req: TReq) => boolean);
 
 export interface Plugin<TReq = http.IncomingMessage, TRes = http.ServerResponse> {
-  (proxyServer: httpProxy, options: Options<TReq, TRes>): void;
+  (proxyServer: httpProxy<TReq, TRes>, options: Options<TReq, TRes>): void;
 }
 
 export interface OnProxyEvent<TReq = http.IncomingMessage, TRes = http.ServerResponse> {

test/types.spec.ts

@@ -193,6 +193,57 @@ describe('http-proxy-middleware TypeScript Types', () => {
       expect(app).toBeDefined();
     });
 
+    // FIXME: contextual types should work with express path middleware
+    // it('should get contextual types from express server', () => {
+    //   const app = express();
+    //   app.use(
+    //     '/',
+    //     middleware({
+    //       router: (req) => req.params,
+    //       pathFilter: (pathname, req) => !!req.params,
+    //       on: {
+    //         error(error, req, res, target) {
+    //           req.params;
+
+    //           // https://www.typescriptlang.org/docs/handbook/2/narrowing.html
+    //           if (res instanceof http.ServerResponse) {
+    //             res.status(200).send('OK');
+    //           }
+    //         },
+    //         proxyReq(proxyReq, req, res, options) {
+    //           req.params;
+    //           res.status(200).send('OK');
+    //         },
+    //         proxyReqWs(proxyReq, req, socket, options, head) {
+    //           req.params;
+    //         },
+    //         proxyRes(proxyRes, req, res) {
+    //           req.params;
+    //           res.status(200).send('OK');
+    //         },
+    //         close(proxyRes, proxySocket, proxyHead) {
+    //           proxyRes.params;
+    //         },
+    //         start(req, res, target) {
+    //           req.params;
+    //           res.status(200).send('OK');
+    //         },
+    //         end(req, res, proxyRes) {
+    //           req.params;
+    //           res.status(200).send('OK');
+    //           proxyRes.params;
+    //         },
+    //         econnreset(error, req, res, target) {
+    //           req.params;
+    //           res.status(200).send('OK');
+    //         },
+    //       },
+    //     })
+    //   );
+
+    //   expect(app).toBeDefined();
+    // });
+
     it('should work with explicit generic custom req & res types', () => {
       interface MyRequest extends http.IncomingMessage {
         myRequestParams: { [key: string]: string };
@@ -260,6 +311,9 @@ describe('http-proxy-middleware TypeScript Types', () => {
       const proxy: RequestHandler<MyRequest, MyResponse> = middleware({
         target: 'http://www.example.org',
         on: {
+          error: (err: Error & { code?: string }, req, res) => {
+            err.code;
+          },
           proxyRes: responseInterceptor(async (buffer, proxyRes, req, res) => {
             req.myRequestParams;
             res.myResponseParams;
@@ -282,17 +336,47 @@ describe('http-proxy-middleware TypeScript Types', () => {
       expect(proxy).toBeDefined();
     });
 
-    it('should work with express.Request with fixRequestBody in plugins', () => {
-      const proxy: RequestHandler<express.Request> = middleware({
+    it('should work with generic types in plugins', () => {
+      const proxy: RequestHandler<express.Request, express.Response> = middleware({
         target: 'http://www.example.org',
         plugins: [
           (proxyServer, options) => {
-            proxyServer.on('proxyReq', fixRequestBody);
+            proxyServer.on('proxyReq', (proxyReq, req, res, options) => {
+              req.params;
+              res.status(200).send('OK');
+            });
           },
         ],
       });
 
       expect(proxy).toBeDefined();
     });
+
+    it('should work with contextual Express types with shipped plugins', () => {
+      const app = express();
+      app.use(
+        middleware({
+          target: 'http://www.example.org',
+          plugins: [
+            (proxyServer, options) => {
+              // fixRequestBody
+              proxyServer.on('proxyReq', fixRequestBody);
+
+              // responseInterceptor
+              proxyServer.on(
+                'proxyRes',
+                responseInterceptor(async (buffer, proxyRes, req, res) => {
+                  req.params;
+                  res.status(200).send('OK');
+                  return buffer;
+                })
+              );
+            },
+          ],
+        })
+      );
+
+      expect(app).toBeDefined();
+    });
   });
 });

yarn.lock

@@ -984,10 +984,10 @@
   dependencies:
     "@types/node" "*"
 
-"@types/http-proxy@^1.17.9":
-  version "1.17.9"
-  resolved "https://registry.yarnpkg.com/@types/http-proxy/-/http-proxy-1.17.9.tgz#7f0e7931343761efde1e2bf48c40f02f3f75705a"
-  integrity sha512-QsbSjA/fSk7xB+UXlCT3wHBy5ai9wOcNDWwZAtud+jXhwOM3l+EYZh8Lng4+/6n8uar0J7xILzqftJdJ/Wdfkw==
+"@types/http-proxy@^1.17.10":
+  version "1.17.10"
+  resolved "https://registry.yarnpkg.com/@types/http-proxy/-/http-proxy-1.17.10.tgz#e576c8e4a0cc5c6a138819025a88e167ebb38d6c"
+  integrity sha512-Qs5aULi+zV1bwKAg5z1PWnDXWmsn+LxIvUGv6E2+OOMYhclZMO+OXd9pYVf2gLykf2I7IV2u7oTHwChPNsvJ7g==
   dependencies:
     "@types/node" "*"