3 files changed, 48 insertions, 4 deletions
diff --git a/src/js/node/http.ts b/src/js/node/http.ts
index a745f9b32..3a283912e 100644
--- a/src/js/node/http.ts
+++ b/src/js/node/http.ts
@@ -972,6 +972,7 @@ export class ServerResponse extends Writable {
     this.#firstWrite = undefined;
     this._writableState.decodeStrings = false;
     this.#deferred = undefined;
+    this.#originalWriteHead = this.writeHead;
   }
 
   req;
@@ -989,9 +990,12 @@ export class ServerResponse extends Writable {
   _removedContLen = false;
   #deferred: (() => void) | undefined = undefined;
   #finished = false;
-
+  #originalWriteHead: (statusCode, statusMessage, headers) => ServerResponse;
   // Express "compress" package uses this
-  _implicitHeader() {}
+  _implicitHeader() {
+    // @ts-ignore
+    this.writeHead(this.statusCode);
+  }
 
   _write(chunk, encoding, callback) {
     if (!this.#firstWrite && !this.headersSent) {
@@ -1058,6 +1062,9 @@ export class ServerResponse extends Writable {
       var data = this.#firstWrite || "";
       this.#firstWrite = undefined;
       this.#finished = true;
+      if (this.writeHead !== this.#originalWriteHead) {
+        this._implicitHeader();
+      }
       this._reply(
         new Response(data, {
           headers: this.#headers,
diff --git a/src/js/out/modules/node/http.js b/src/js/out/modules/node/http.js
index 13ee7fded..9cfaccd04 100644
--- a/src/js/out/modules/node/http.js
+++ b/src/js/out/modules/node/http.js
@@ -630,7 +630,7 @@ class OutgoingMessage extends Writable {
 class ServerResponse extends Writable {
   constructor({ req, reply }) {
     super();
-    this.req = req, this._reply = reply, this.sendDate = !0, this.statusCode = 200, this.headersSent = !1, this.statusMessage = void 0, this.#controller = void 0, this.#firstWrite = void 0, this._writableState.decodeStrings = !1, this.#deferred = void 0;
+    this.req = req, this._reply = reply, this.sendDate = !0, this.statusCode = 200, this.headersSent = !1, this.statusMessage = void 0, this.#controller = void 0, this.#firstWrite = void 0, this._writableState.decodeStrings = !1, this.#deferred = void 0, this.#originalWriteHead = this.writeHead;
   }
   req;
   _reply;
@@ -647,7 +647,9 @@ class ServerResponse extends Writable {
   _removedContLen = !1;
   #deferred = void 0;
   #finished = !1;
+  #originalWriteHead;
   _implicitHeader() {
+    this.writeHead(this.statusCode);
   }
   _write(chunk, encoding, callback) {
     if (!this.#firstWrite && !this.headersSent) {
@@ -694,7 +696,9 @@ class ServerResponse extends Writable {
   _final(callback) {
     if (!this.headersSent) {
       var data = this.#firstWrite || "";
-      this.#firstWrite = void 0, this.#finished = !0, this._reply(new Response(data, {
+      if (this.#firstWrite = void 0, this.#finished = !0, this.writeHead !== this.#originalWriteHead)
+        this._implicitHeader();
+      this._reply(new Response(data, {
         headers: this.#headers,
         status: this.statusCode,
         statusText: this.statusMessage ?? STATUS_CODES[this.statusCode]
diff --git a/test/js/node/http/node-http.test.ts b/test/js/node/http/node-http.test.ts
index 3e7da9d34..0e7b3ca13 100644
--- a/test/js/node/http/node-http.test.ts
+++ b/test/js/node/http/node-http.test.ts
@@ -146,6 +146,29 @@ describe("node:http", () => {
             res.end("Path correct!\n");
             return;
           }
+          if (reqUrl.pathname === "/customWriteHead") {
+            function createWriteHead(prevWriteHead, listener) {
+              let fired = false;
+              return function writeHead() {
+                if (!fired) {
+                  fired = true;
+                  listener.call(this);
+                }
+                return prevWriteHead.apply(this, arguments);
+              };
+            }
+
+            function addPoweredBy() {
+              if (!this.getHeader("X-Powered-By")) {
+                this.setHeader("X-Powered-By", "Bun");
+              }
+            }
+
+            res.writeHead = createWriteHead(res.writeHead, addPoweredBy);
+            res.setHeader("Content-Type", "text/plain");
+            res.end("Hello World");
+            return;
+          }
         }
 
         res.writeHead(200, { "Content-Type": "text/plain" });
@@ -507,6 +530,16 @@ describe("node:http", () => {
         req.end();
       });
     });
+    it("reassign writeHead method, issue#3585", done => {
+      runTest(done, (server, serverPort, done) => {
+        const req = request(`http://localhost:${serverPort}/customWriteHead`, res => {
+          expect(res.headers["content-type"]).toBe("text/plain");
+          expect(res.headers["x-powered-by"]).toBe("Bun");
+          done();
+        });
+        req.end();
+      });
+    });
   });
 
   describe("signal", () => {