How to move socket routing to a separate file?

Question

Node.js

io.on('connection', (socket) => {
  socket.on('INVENTORY_CONNECT', (data) => {
    socket.join(data);
  });
  socket.on('disconnect', (data) => {
    console.log('CLIENT DISCONECT');
  });
  socket.on('DRAG', (data) => {
    const { inventoryID, HTML_ID_ELEMENT,coords} = data;
    let msg = { HTML_ID_ELEMENT,coords };
    socket.broadcast.to(inventoryID).emit('CLEAR', msg);
  });
  socket.on('UNDO', (data) => {
    const { userInventoryId, Coords, activeElem } = data;
    let msg = {
      Coords,
      activeElem
    };
    socket.broadcast.to(userInventoryId).emit('UNDO', msg);
  });
});

There is such a code. How to move the routing control i.e. socket.on to a separate file? Without the fact that I'm resorting to namespace?