fix(types): widen Filter callback return type

src/path-filter.ts

@@ -36,7 +36,7 @@ export function matchPathFilter<TReq extends http.IncomingMessage = http.Incomin
   // custom matching
   if (typeof pathFilter === 'function') {
     const pathname = getUrlPathName(uri) as string;
-    return pathFilter(pathname, req as TReq);
+    return Boolean(pathFilter(pathname, req as TReq));
   }
 
   throw new Error(ERRORS.ERR_CONTEXT_MATCHER_GENERIC);

src/types.ts

@@ -21,7 +21,7 @@ export interface RequestHandler<
 export type Filter<TReq extends http.IncomingMessage = http.IncomingMessage> =
   | string
   | string[]
-  | ((pathname: string, req: TReq) => boolean);
+  | ((pathname: string, req: TReq) => boolean | string | RegExpMatchArray | null);
 
 /**
  * @see {@link https://github.com/chimurai/http-proxy-middleware/tree/master#defineplugin-helper `definePlugin()`} to define a http-proxy-middleware plugin.

test/types.spec.ts

@@ -52,6 +52,24 @@ describe('http-proxy-middleware TypeScript Types', () => {
       expect(proxy).toBeDefined();
     });
 
+    it('should create proxy with truthy filter', () => {
+      const proxy = middleware({
+        ...options,
+        pathFilter: (path, req) => path.match('^/api') && req.method === 'GET',
+      });
+      expect(proxy).toBeDefined();
+    });
+
+    it('should create proxy with truthy regex match filter', () => {
+      const proxy = middleware({ ...options, pathFilter: (path, req) => path.match('^/api') });
+      expect(proxy).toBeDefined();
+    });
+
+    it('should create proxy with truthy regex test filter', () => {
+      const proxy = middleware({ ...options, pathFilter: (path, req) => /^\/api/.test(path) });
+      expect(proxy).toBeDefined();
+    });
+
     it('should create proxy with manual websocket upgrade function', () => {
       const proxy = middleware({ ...options, pathFilter: (path, req) => true });
       expect(proxy.upgrade).toBeDefined();