How to constantly receive data from a socket?

Question

Node.js

Good afternoon, I understand that it is not clear from the name what I need, I will try to describe.
there are 3 sides Playlist.html -> app.js ->
Playlist.html client sends to app,js playlist, client should get data from app.js when connecting.
Looks like this
Playlist.html
socket.emit('songchanged', stringTableCur);
App.js

socket.on('songchanged', function(changed){
   console.log(changed);
});

And the client must do something similar
socket.emit('getSong');
. But it is clear that the design will not work

socket.on('songchanged', function(changed){
  socket.on('getSong, function(data){
      emit...
  })
});

Option to enter in a json file, maybe there is another option?