React Native

Socket Send/Receive 16-bit Integers

Demonstrates sending and receiving 16-bit integers over a socket connection using either big-endian or little-endian byte ordering. React Native

import { Socket } from '@chilkat/react-native'

async function chilkatExample() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  const sock = new Socket();

  // --------------------------------------------------------------------
  // This example uses the public TCP echo service at https://tcpbin.com/
  // --------------------------------------------------------------------

  const useTls = false;
  const port = 4242;
  const maxWaitMs = 5000;
  try {
    await sock.connectAsync('tcpbin.com', port, useTls, maxWaitMs);
  } catch {
    console.log(sock.lastErrorText);
    return;
  }

  // Wait a max of 2 seconds for a response..
  sock.maxReadIdleMs = 2000;

  // Send a 16-bit integer using big-endian byte ordering (also called network byte order)
  // 12022 decimal = 2EF6 hex
  let value = 12022;
  let bigEndian = true;
  await sock.sendInt16Async(value, bigEndian);
  // Send it again, because we'll read it two different ways..
  await sock.sendInt16Async(value, bigEndian);

  // The tcpbin.com echo server only echoes after receiving an LF (linefeed char)
  await sock.sendByteAsync(10);

  // Let's see hex values of the 2 bytes sent in network byte order (big-endian)
  // (The echo server sends back exactly the bytes received.)
  let hexStr = await sock.receiveNBytesENCAsync(2, 'hex');

  // In the big-ending byte order, the byte order is most significant byte to least significant,
  // therefore we should see the bytes in the order 0x2E 0xF6.
  console.log('Expecting big-endian 2EF6');
  console.log(hexStr);

  // Let's read directly to an integer..
  await sock.receiveInt16Async(bigEndian, true);
  console.log('Expecting 12022');
  console.log(`Received: ${sock.receivedInt}`);

  // Consume the LF that gets echoed back..
  await sock.receiveByteAsync(true);

  // --------------------------------------------------------------------
  // Let's do the same thing, but with little-endian byte ordering.

  console.log('----');

  // 12022 decimal = 2EF6 hex, but little-endian byte ordering will send the bytes in the order 0xF6 0x2E
  value = 12022;
  bigEndian = false;
  await sock.sendInt16Async(value, bigEndian);
  await sock.sendInt16Async(value, bigEndian);
  await sock.sendByteAsync(10);

  hexStr = await sock.receiveNBytesENCAsync(2, 'hex');

  console.log('Expecting little-endian F62E');
  console.log(hexStr);

  await sock.receiveInt16Async(bigEndian, true);
  console.log('Expecting 12022');
  console.log(`Received: ${sock.receivedInt}`);

  // Consume the LF that gets echoed back..
  await sock.receiveByteAsync(true);

  await sock.closeAsync(1000);

  // Output:

  // Expecting big-endian 2EF6
  // 2EF6
  // Expecting 12022
  // Received: 12022
  // ----
  // Expecting little-endian F62E
  // F62E
  // Expecting 12022
  // Received: 12022
}