WebSocketHandler.drain

interface ServerWebSocket<T = undefined>

Bun.serve({
  websocket: {
    open(ws) {
      console.log("Connected", ws.remoteAddress);
    },
    message(ws, data) {
      console.log("Received", data);
      ws.send(data);
    },
    close(ws, code, reason) {
      console.log("Disconnected", code, reason);
    },
  }
});

• binaryType?: 'arraybuffer' | 'uint8array' | 'nodebuffer'

  Sets how binary data is returned in events.

  • if nodebuffer, binary data is returned as Buffer objects. (default)
  • if arraybuffer, binary data is returned as ArrayBuffer objects.
  • if uint8array, binary data is returned as Uint8Array objects.

  let ws: WebSocket;
  ws.binaryType = "uint8array";
  ws.addEventListener("message", ({ data }) => {
    console.log(data instanceof Uint8Array); // true
  });
  
• data: T

  Custom data that you can assign to a client, can be read and written at any time.

  import { serve } from "bun";
  
  serve({
    fetch(request, server) {
      const data = {
        accessToken: request.headers.get("Authorization"),
      };
      if (server.upgrade(request, { data })) {
        return;
      }
      return new Response();
    },
    websocket: {
      open(ws) {
        console.log(ws.data.accessToken);
      }
    }
  });
  
• readonly readyState: WebSocketReadyState

  The ready state of the client.

  • if 0, the client is connecting.
  • if 1, the client is connected.
  • if 2, the client is closing.
  • if 3, the client is closed.

  console.log(socket.readyState); // 1
  
• readonly remoteAddress: string

  The IP address of the client.

  console.log(socket.remoteAddress); // "127.0.0.1"
  
• close(code?: number, reason?: string): void

  Closes the connection.

  Here is a list of close codes:

  • 1000 means "normal closure" (default)
  • 1009 means a message was too big and was rejected
  • 1011 means the server encountered an error
  • 1012 means the server is restarting
  • 1013 means the server is too busy or the client is rate-limited
  • 4000 through 4999 are reserved for applications (you can use it!)

  To close the connection abruptly, use terminate().

  @param code

  The close code to send

  @param reason

  The close reason to send

• cork<T = unknown>(callback: (ws: ServerWebSocket<T>) => T): T

  Batches send() and publish() operations, which makes it faster to send data.

  The message, open, and drain callbacks are automatically corked, so you only need to call this if you are sending messages outside of those callbacks or in async functions.

  @param callback

  The callback to run.

  ws.cork((ctx) => {
    ctx.send("These messages");
    ctx.sendText("are sent");
    ctx.sendBinary(new TextEncoder().encode("together!"));
  });
  
• getBufferedAmount(): number
• isSubscribed(topic: string): boolean

  Is the client subscribed to a topic?

  @param topic

  The topic name.

  ws.subscribe("chat");
  console.log(ws.isSubscribed("chat")); // true
  
• ping(data?: string | BufferSource): number

  Sends a ping.

  @param data

  The data to send

• pong(data?: string | BufferSource): number

  Sends a pong.

  @param data

  The data to send

• publish(topic: string, data: string | BufferSource, compress?: boolean): number

  Sends a message to subscribers of the topic.

  @param topic

  The topic name.

  @param data

  The data to send.

  @param compress

  Should the data be compressed? If the client does not support compression, this is ignored.

  ws.publish("chat", "Hello!");
  ws.publish("chat", "Compress this.", true);
  ws.publish("chat", new Uint8Array([1, 2, 3, 4]));
  
• publishBinary(topic: string, data: BufferSource, compress?: boolean): number

  Sends a binary message to subscribers of the topic.

  @param topic

  The topic name.

  @param data

  The data to send.

  @param compress

  Should the data be compressed? If the client does not support compression, this is ignored.

  ws.publish("chat", new TextEncoder().encode("Hello!"));
  ws.publish("chat", new Uint8Array([1, 2, 3, 4]), true);
  
• publishText(topic: string, data: string, compress?: boolean): number

  Sends a text message to subscribers of the topic.

  @param topic

  The topic name.

  @param data

  The data to send.

  @param compress

  Should the data be compressed? If the client does not support compression, this is ignored.

  ws.publish("chat", "Hello!");
  ws.publish("chat", "Compress this.", true);
  
• send(data: string | BufferSource, compress?: boolean): number

  Sends a message to the client.

  @param data

  The data to send.

  @param compress

  Should the data be compressed? If the client does not support compression, this is ignored.

  ws.send("Hello!");
  ws.send("Compress this.", true);
  ws.send(new Uint8Array([1, 2, 3, 4]));
  
• sendBinary(data: BufferSource, compress?: boolean): number

  Sends a binary message to the client.

  @param data

  The data to send.

  @param compress

  Should the data be compressed? If the client does not support compression, this is ignored.

  ws.send(new TextEncoder().encode("Hello!"));
  ws.send(new Uint8Array([1, 2, 3, 4]), true);
  
• sendText(data: string, compress?: boolean): number

  Sends a text message to the client.

  @param data

  The data to send.

  @param compress

  Should the data be compressed? If the client does not support compression, this is ignored.

  ws.send("Hello!");
  ws.send("Compress this.", true);
  
• subscribe(topic: string): void

  Subscribes a client to the topic.

  @param topic

  The topic name.

  ws.subscribe("chat");
  
• terminate(): void

  Abruptly close the connection.

  To gracefully close the connection, use close().

• unsubscribe(topic: string): void

  Unsubscribes a client to the topic.

  @param topic

  The topic name.

  ws.unsubscribe("chat");