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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('any')
  .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() },
      })
    }
  })