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Creates an event handler that listens to changes.

  • By default, Broadcast and Presence are enabled for all projects.
  • By default, listening to database changes is disabled for new projects due to database performance and security concerns. You can turn it on by managing Realtime's replication.
  • You can receive the "previous" data for updates and deletes by setting the table's REPLICA IDENTITY to FULL (e.g., ALTER TABLE your_table REPLICA IDENTITY FULL;).
  • Row level security is not applied to delete statements. When RLS is enabled and replica identity is set to full, only the primary key is sent to clients.
Parameters
    type
    REQUIRED
    "broadcast"

    One of "broadcast", "presence", or "postgres_changes".

    filter
    REQUIRED
    object

    Custom object specific to the Realtime feature detailing which payloads to receive.

    callback
    REQUIRED
    function

    Function to be invoked when event handler is triggered. 


supabase
  .channel('room1')
  .on('broadcast', { event: 'cursor-pos' }, payload => {
    console.log('Cursor position received!', payload)
  })
  .subscribe((status) => {
    if (status === 'SUBSCRIBED') {
      channel.send({
        type: 'broadcast',
        event: 'cursor-pos',
        payload: { x: Math.random(), y: Math.random() },
      })
    }
  })
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