event-source-2.html

<script src="event-source-2.js"></script>

event-source-2.js

document.addEventListener('DOMContentLoaded', function () {

  var eventSrc  = new EventSource('event-source-2.php');
  
  console.group('EventSource Created');
  console.dir( eventSrc );
  console.groupEnd();
  
  eventSrc.addEventListener('open', function (event) {
    console.time('Time Elapsed between open and message');
    console.log(event.type);
  });
  
  eventSrc.addEventListener('message', function (event) {
    
    console.timeEnd('Time Elapsed between open and message');
    console.log(event);
    console.dir( JSON.parse(event.data) );
  
  });
}, false);

event-source-2.php

<?php
header("Content-Type: text/event-stream\n\n");

// despite not having the while(true){}
// this seems to repeat pushing messages to the client
echo 'data: ' . json_encode(
                  array(
                    0 => array( 
                      'time' => time(), 
                      'message' => 'Some kind of foo'
                    ), 
                    1 => array( 
                      'time' => time(), 
                      'message' => 'Some kind of quux' 
                    )
                  )
                ) . "\n";
?>