从另一个PHP中的函数执行外部JavaScript函数

I am new to php, Please give me a help if anyone know how to execute an external JavaScript function from a function in another PHP file. (or using Ajax).

In my code (see the comment):

In index.php->

<script type="text/javascript">
function OnUnityReady()

{

u.getUnity().SendMessage("test", "SubmitInputValue", "name");  
}
</script>

In chatApp.php ->

<?php

 class pfcCommand
 {

function write($chan, $nick, $cmd, $param)
  {

    $data .= $nick."\t";
    $data .= $cmd."\t";
    $data .= $param;

    .
    .

    $this->setMeta("channelid-to-msg", $this->encode($chan), $msgid, $data);

   //FROM HERE, I NEED TO EXECUTE OnUnityReady() FUNCTION in index.html 
   //IN EVERY TIME WHEN EXECUTE THIS write FUNCTION


return $msgid;

}
}
?>

You cannot execute a javascript function from within a php script. Especially since javascript is parsed by your browser, using file_get_contents() or cURL wouldn't work. Find a way to replicate the JavaScript function in PHP :/