Websocket Example

wss.js

import WebSocket from 'ws';

const url = `wss://ws.postman-echo.com/raw`
const ws = new WebSocket(url);

const timeout = setTimeout(function () {
  console.log('Failed to receive expected data within timeout. Terminating the WebSocket connection.')
  ws.close()
  throw new Error('Failed to receive expected data within timeout.')
}, 10000)

ws.on('error', console.error)

ws.on('message', function message(data) {
  const jsonData = JSON.parse(data);
  if (jsonData.type === "KEEP_ALIVE") {
    console.log('Received keep alive')
  } else if (jsonData.type === "CONN_ERROR") {
    console.log('Received CONN_ERROR')
    ws.close()
  } else if (jsonData.type === "SUBACK") {
    // The SUBACK message is sent in response to the SUB message from sendMessage()
    // After receiving a SUBACK, we can end the check.
    console.log('Received suback. Terminating the connection.')
    // Close the connection
    ws.close()
  }
})

ws.on('close', function close() {
  console.log('disconnected');
  // Clear the timeout since the WebSocket connection has been closed.
  clearTimeout(timeout)
})

async function sendMessage(id) {
  const payload = `{
  "action": "subscribe",
    "channels": [
      "channel1",
      "channel2",
      "channel3"
    ]
  }`
  ws.send(JSON.stringify(payload));
}