Calling a php file with jquery - session var is not read - php

Question

this is the code that I have to call my index.php file.
<script type="text/javascript">
$('button').click(function(){
$.ajax({url: 'permiteCookie.php'});
document.getElementById('div_cookies').style.display = 'none';
return false;
})
</script>
<?php
session_start();
if (!isset($_SESSION['permiteCookie'])){
?>
<div class="div_cookies" style="display: block;">
<div>
<div>
<div class="cookies_botoes">
<div class="cookies_bt2">
<button id="button" name="button" type="button">Close</button>
<a id="button" name="button" href="javascript:void(null);">Close</a></div>
</div>
</div>
</div>
</div>
<?php
}
?>
and this is the code that I have in the file permiteCookie.php
<?php
session_start();
$_SESSION['permiteCookie']=1;
?>
Problem: I cant access to the $_SESSION['permiteCookie'] in the index.php file.
What am I doing wrong?

Answer 1

The script is running before the DOM is ready. You'll need to wrap it in a $(document).ready() handler:
<script type="text/javascript">
$(document).ready(function(){
$('button').click(function(){
$.ajax({url: 'permiteCookie.php'});
document.getElementById('div_cookies').style.display = 'none';
return false;
});
});
</script>
And as long as you're using jQuery, why use the plain DOM to hide the div?
$('#div_cookies').hide();

Answer 2

if I'm not mistaken, because session_start() affects the page headers, it needs to be at the top of the page, preferably the first line of code.
i.e. add this segment to the very top of index.php :
<?php
session_start();
if (!isset($_SESSION['permiteCookie'])){
?>