react-native-tcp-windows

TCP sockets communication for React Native Windows (RNW).

Supports multiple concurrent connections. Every connection is identified by a connectionId ("address:port" for clients, "server:port" for servers) returned by connectToServer/startServer; all other calls and every event are keyed by it. Connect, write, and close run off the JS thread — a slow or stalled peer cannot block the UI — and writes fail with false after a deadline instead of hanging.

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Installation

npm install react-native-tcp-windows

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Usage

import React, { useEffect, useState } from 'react';
import {
  connectToServer,
  closeConnection,
  writeString,
  bytesToString,
  makeConnectionId,
  eventEmitter,
  TCP_SOCKET_EVENTS,
  type DataReceivedEvent,
} from 'react-native-tcp-windows';

const SERVER_ADDRESS = '127.0.0.1';
const SERVER_PORT = 5000;
const CONNECTION_ID = makeConnectionId(SERVER_ADDRESS, SERVER_PORT);

export default function App() {
  const [log, setLog] = useState<string[]>([]);

  useEffect(() => {
    const connect = async () => {
      try {
        const connectionId = await connectToServer(SERVER_ADDRESS, SERVER_PORT);
        appendLog(`✅ Connected: ${connectionId}`);
      } catch (error: any) {
        appendLog(`❌ Connection failed: ${error.message || error}`);
      }
    };

    connect();

    const subscription = eventEmitter.addListener(
      TCP_SOCKET_EVENTS.DATA_RECEIVED,
      (event: DataReceivedEvent) => {
        // Events from every open connection arrive here — filter on the id.
        if (event.connectionId !== CONNECTION_ID) return;
        const text = bytesToString(event.data);
        appendLog(`📥 Received: ${text}`);
      }
    );

    return () => {
      subscription.remove();
      closeConnection(CONNECTION_ID).then(() => appendLog('🔌 Connection closed'));
    };
  }, []);

  const appendLog = (message: string) => {
    setLog((logs) => [...logs, message]);
  };

  const sendMessage = async (message: string) => {
    const success = await writeString(CONNECTION_ID, message);
    if (success) appendLog(`📤 Sent: ${message}`);
    else appendLog(`⚠️ Failed to send message`);
  };

  return (
    // Your UI components here
  );
}

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API

Function	Description	Returns
connectToServer	Connect as a TCP client; resolves with the connectionId. Reconnecting to the same address:port replaces the existing connection.	Promise<string>
startServer	Start a TCP server; resolves with the connectionId	Promise<string>
closeConnection	Close the given connection	Promise<string>
write	Send raw bytes (number array) on a connection	Promise<boolean>
writeString	Send UTF-8 string data on a connection	Promise<boolean>
writeJson	Send JSON data as UTF-8 string on a connection	Promise<boolean>
getConnectionStatus	Get status of the given connection	Promise<boolean>
makeConnectionId	Compute a client connectionId without connecting	string
makeServerConnectionId	Compute a server connectionId without starting it	string
bytesToString	Convert received byte array to string	string
bytesToJson	Convert received byte array to parsed JSON object	any

write resolves false (rather than rejecting) when the send fails or the peer stalls past the internal deadline; it rejects only when the connection does not exist.

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Events

You can listen to socket events via the exported eventEmitter. Every event payload includes the connectionId it belongs to:

Event Name	Event Data Type	Description
TCP_SOCKET_EVENTS.DATA_RECEIVED	DataReceivedEvent	Fired when data is received
TCP_SOCKET_EVENTS.CLIENT_CONNECTED	ClientConnectedEvent	Fired when a client connects
TCP_SOCKET_EVENTS.CLIENT_DISCONNECTED	ClientDisconnectedEvent	Fired when a client disconnects
TCP_SOCKET_EVENTS.CONNECTION_STATUS_CHANGED	ConnectionStatusChangedEvent	Fired when connection status changes

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Types

export interface DataReceivedEvent {
  connectionId: string;
  data: number[];
}

export interface ClientConnectedEvent {
  connectionId: string;
  clientAddress: string;
}

export interface ClientDisconnectedEvent {
  connectionId: string;
  clientAddress: string;
}

export interface ConnectionStatusChangedEvent {
  connectionId: string;
  connected: boolean;
  message: string;
}

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Migrating from 0.2.x

1.0.0 is a breaking change: the module went from a single implicit connection to a keyed registry.

• closeConnection(), write(data), getConnectionStatus() now take a connectionId as their first argument.
• connectToServer/startServer resolve with the connectionId instead of a message; keep it (or recompute it with makeConnectionId).
• Event payloads gained connectionId; filter on it if you open more than one connection.

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Contributing

See the CONTRIBUTING.md for contribution guidelines.

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License

MIT

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Made with create-react-native-library

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