How to execute a method on rails via action cable

action_cable_send_backend.js

socket = new WebSocket('ws://localhost:3000/api/v1/action_cable');
const onMessage = (ws, store) => evt => {
  let msg = JSON.parse(evt.data);

  if (msg.type === "ping") {
    return;
  }
  console.log("FROM RAILS: ", msg);
}
socket.onmessage = onMessage(socket);

// you need to subscribe to the channel first
var msg = {
  command: 'subscribe',
  identifier: JSON.stringify({
    channel: 'ReadingsChannel',
  }),
};
socket.send(JSON.stringify(msg));

// the method foobar is going to be executed on Rails (channel file)
var msg = {
  command: 'message',
  identifier: JSON.stringify({
    channel: 'ReadingsChannel',
  }),
  data: JSON.stringify({
    action: 'foobar',
    code: 1234
  }),
};
socket.send(JSON.stringify(msg));