PHP log out with AJAX call - php

Question

I have a logout function that looks like this.
if ($_GET["argument"]=='logOut'){
if(session_id() == '') {
session_start();
}
session_unset();
session_destroy();
$host = $_SERVER['HTTP_HOST'];
$extra = 'index.php';
header("Location: http://$host/$extra");
exit;
}
My problem is that, If I inspect the page and look at the Network preview and response, it looks 'fine'.
There are two php files listed that was processed.
http://localhost:5000/inc/mainScripts.php?argument=logOut
which is where the function is located.
and http://localhost:5000/index.php
Which is where i would like to be redirected.
The Response tab in the Network of the inspect page area in chrome
contains the full login html page login.php but in the browser it remains in the same place. Like the header command has never been called.
What Am I doing wrong?
HTML AJAX call to this function:
$("#logout_btn").click(function() {
$.ajax({
url: './inc/mainScripts.php?argument=logOut'
})
});
SOLUTION
AJAX
$("#logout_btn").click(function() {
$.ajax({
url: './inc/mainScripts.php?argument=logOut',
success: function(data){
window.location.href = data;
}
});
});
PHP
if ($_GET["argument"]=='logOut'){
if(session_id() == '') {
session_start();
}
session_unset();
session_destroy();
$host = $_SERVER['HTTP_HOST'];
$link = "http://$host/index.php";
echo $link;
}

Answer 1

Try this instead.
if( isset($_GET['argument']) && $_GET['argument'] == 'logOut' && !empty( session_id() ) ) {
session_destroy();
header("Location: http://" . $_SERVER['HTTP_HOST'] . "/index.php");
exit;
}
Edit: If you're using AJAX, it'd be easier to send the url from your php script back to your javascript and redirect from there.

Answer 2

You are probably running into the same common problem that many people run into when people first start to program in PHP.
Calls to header() only works when there are NO previous HTML output generated. If there are any HTML output generated, even just a single space, calls to header() will fail. To get around this problem, use functions such as ob_start() and ob_end_flush().