functions.php

function eventSourceTest() {
  header("Content-Type: text/event-stream\n\n");

  $counter = rand(1, 10);
  echo "Bajs $counter eaaa";

  while (1) {
    // Every second, sent a "ping" event.
    echo "event: ping\n";
    $curDate = @date(DATE_ISO8601);
    echo 'data: {"time": "' . $curDate . '"}';
    echo "\n\n";

    // Send a simple message at random intervals.

    $counter--;

    if (!$counter) {
      echo 'data: This is a message at time ' . $curDate . "\n\n";
      $counter = rand(1, 10);
    }

    ob_flush();
    flush();
    sleep(1);
  }

  exit();
}

add_action('wp_ajax_test', 'eventSourceTest');
add_action('wp_ajax_nopriv_test', 'eventSourceTest');