[ServerWebSocket] `binaryType` now defaults to `"nodebuffer"`

Previously, this defaulted to "uint8array", so this shouldn't be a breaking change unless you make use of `.slice()` in which case it will now be a reference to the same ArrayBuffer rather than a clone.

The rationale for this change is most usages of Uint8Array on the server need a little more than just the bytes. Many npm packages expect Buffer rather than Uint8Array. Directly returning it for binary websocket messages is faster than creating another one.

3 files changed, 15 insertions, 14 deletions

diff --git a/packages/bun-types/bun.d.ts b/packages/bun-types/bun.d.ts
index d06a7235e..5558e2db7 100644
--- a/packages/bun-types/bun.d.ts
+++ b/packages/bun-types/bun.d.ts
@@ -1334,7 +1334,9 @@ declare module "bun" {
     /**
      * Configure the {@link WebSocketHandler.message} callback to return a {@link ArrayBuffer} or {@link Buffer} instead of a {@link Uint8Array}
      *
-     * @default "uint8array"
+     * @default "nodebuffer"
+     *
+     * In Bun v0.6.2 and earlier, this defaulted to "uint8array"
      */
     binaryType?: "arraybuffer" | "uint8array" | "nodebuffer";
   }
diff --git a/src/bun.js/api/server.zig b/src/bun.js/api/server.zig
index 59410d0cb..2ce7347c0 100644
--- a/src/bun.js/api/server.zig
+++ b/src/bun.js/api/server.zig
@@ -3256,7 +3256,7 @@ pub const ServerWebSocket = struct {
     this_value: JSValue = .zero,
     websocket: uws.AnyWebSocket = undefined,
     closed: bool = false,
-    binary_type: JSC.BinaryType = .Uint8Array,
+    binary_type: JSC.BinaryType = .Buffer,
     opened: bool = false,
 
     pub usingnamespace JSC.Codegen.JSServerWebSocket;
@@ -3355,17 +3355,17 @@ pub const ServerWebSocket = struct {
                     str.markUTF8();
                     break :brk str.toValueGC(globalObject);
                 },
-                .binary => if (this.binary_type == .Uint8Array)
+                .binary => if (this.binary_type == .Buffer)
                     JSC.ArrayBuffer.create(
                         globalObject,
                         message,
-                        .Uint8Array,
+                        .Buffer,
                     )
-                else if (this.binary_type == .Buffer)
+                else if (this.binary_type == .Uint8Array)
                     JSC.ArrayBuffer.create(
                         globalObject,
                         message,
-                        .Buffer,
+                        .Uint8Array,
                     )
                 else
                     JSC.ArrayBuffer.create(
diff --git a/test/js/bun/websocket/websocket-server.test.ts b/test/js/bun/websocket/websocket-server.test.ts
index 014178b84..3868d0267 100644
--- a/test/js/bun/websocket/websocket-server.test.ts
+++ b/test/js/bun/websocket/websocket-server.test.ts
@@ -171,7 +171,6 @@ describe("websocket server", () => {
 
   it("close inside open", async () => {
     var resolve: () => void;
-    console.trace("here");
     var server = serve({
       port: 0,
       websocket: {
@@ -441,7 +440,7 @@ describe("websocket server", () => {
           // Then after nodebuffer, we switch it to "arraybuffer"
           // and then we're done
           switch (ws.binaryType) {
-            case "uint8array": {
+            case "nodebuffer": {
               for (let badType of [
                 123,
                 NaN,
@@ -457,20 +456,20 @@ describe("websocket server", () => {
                   ws.binaryType = badType;
                 }).toThrow();
               }
-              expect(ws.binaryType).toBe("uint8array");
-              ws.binaryType = "nodebuffer";
               expect(ws.binaryType).toBe("nodebuffer");
+              ws.binaryType = "uint8array";
+              expect(ws.binaryType).toBe("uint8array");
               expect(msg instanceof Uint8Array).toBe(true);
-              expect(Buffer.isBuffer(msg)).toBe(false);
+              expect(Buffer.isBuffer(msg)).toBe(true);
               break;
             }
 
-            case "nodebuffer": {
-              expect(ws.binaryType).toBe("nodebuffer");
+            case "uint8array": {
+              expect(ws.binaryType).toBe("uint8array");
               ws.binaryType = "arraybuffer";
               expect(ws.binaryType).toBe("arraybuffer");
               expect(msg instanceof Uint8Array).toBe(true);
-              expect(Buffer.isBuffer(msg)).toBe(true);
+              expect(Buffer.isBuffer(msg)).toBe(false);
               break;
             }