[node:http] Fix return type for `getHeader()` (#3007)

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

2 files changed, 15 insertions, 7 deletions

diff --git a/src/bun.js/http.exports.js b/src/bun.js/http.exports.js
index c05d70d9a..d9c44836b 100644
--- a/src/bun.js/http.exports.js
+++ b/src/bun.js/http.exports.js
@@ -56,6 +56,12 @@ function isValidTLSArray(obj) {
   }
 }
 
+function getHeader(headers, name) {
+  if (!headers) return;
+  const result = headers.get(name);
+  return result == null ? undefined : result;
+}
+
 var FakeSocket = class Socket extends Duplex {
   bytesRead = 0;
   bytesWritten = 0;
@@ -858,8 +864,7 @@ export class OutgoingMessage extends Writable {
   flushHeaders() {}
 
   getHeader(name) {
-    if (!this.#headers) return;
-    return this.#headers.get(name);
+    return getHeader(this.#headers, name);
   }
 
   getHeaders() {
@@ -1092,13 +1097,13 @@ export class ServerResponse extends Writable {
   flushHeaders() {}
 
   getHeader(name) {
-    if (!this.#headers) return;
-    return this.#headers.get(name);
+    return getHeader(this.#headers, name);
   }
 
   getHeaders() {
-    if (!this.#headers) return kEmptyObject;
-    return this.#headers.toJSON();
+    var headers = this.#headers;
+    if (!headers) return kEmptyObject;
+    return headers.toJSON();
   }
 
   getHeaderNames() {
diff --git a/test/js/node/http/node-http.test.ts b/test/js/node/http/node-http.test.ts
index 726453217..b1910a1f7 100644
--- a/test/js/node/http/node-http.test.ts
+++ b/test/js/node/http/node-http.test.ts
@@ -398,8 +398,11 @@ describe("node:http", () => {
           });
           res.on("error", err => done(err));
         });
-        req.end();
         expect(req.getHeader("X-Test")).toBe("test");
+        // node returns undefined
+        // Headers returns null
+        expect(req.getHeader("X-Not-Exists")).toBe(undefined);
+        req.end();
       });
     });