How to set a stream for a specific user with mongodb streams

I am trying to set up a mongodb stream for a specific user but the thing is that you won’t be able to know what someone will give as a username, in this case the field is called: charactername.

For this project I am using: mongodb, express, nodejs and socket.io. The socket.io broadcasts it to the frontend and refreshed the page once there is a change in the database. But the thing is right now if something is changed in the collection “users” the refresh happens for every user instead of a specific user of whose document gets updated.

This is the code for the backend:

User.watch([{ $match: {
operationType: 
{$in: ['update']},
"updateDescription.updatedFields.charactername": ""   //What should I put here ?
}}]).
on('change', data => {
  console.log('Update action triggered');
  console.log(new Date(), data.updateDescription.updatedFields);
  console.log(data)
  io.emit("DBchange", data);
});

This is the code for the front end:

<script>

socket.on("DBchange", (data) => {
console.log(data)
location.reload()
});

</script>

How can I fix this issue?