js + php服务器推送see(自定义推送时间)

 //javascript code

 var source = new EventSource("./main.php");

 source.onmessage=function(event){

     document.write(event.data);

 }

 //main.php

 <?php
 header('Content-Type: text/event-stream');//服务端推送事件特定的MIME类型
 header('Cache-Control: no-cache');//禁止缓存
 echo 'retry:1000'.PHP_EOL;//推送时间(每多少毫秒推送一次, 默认为3000ms/次)

 echo "data:";
 echo Time()."<br/>";
 echo "\n\n";

 ?>