Using variables defined in functions.php WORDPRESS - php

Question

I have a variable that is being pulled from a jQuery into php in my functions.php file.
But I'm unable to use it in a page.
When I echo it from functions.php, it appears in the console in chrome, but has a 0 appended..
If I try to echo it in my template page, I get nothing.
Code below.
jQuery
var pie = 131;
$.ajax({
url: ajaxurl, //super global supplied by Wordpress; do not change
type: 'POST',
data: {
action: 'get_post_id', //this is correct
pie : pie
},
success: function (data){
console.log(data);
}
});
functions.php
add_action('wp_head','pluginname_ajaxurl');
function pluginname_ajaxurl() {
?>
<script type="text/javascript">
var ajaxurl = '<?php echo admin_url('admin-ajax.php'); ?>';
</script>
<?php
}
add_action( 'wp_ajax_nopriv_get_post_id', 'my_ajax_function' );
add_action( 'wp_ajax_get_post_id', 'my_ajax_function' );
function my_ajax_function() {
$new_pie = isset($_POST['pie']) ? $_POST['pie'] : false;
echo($new_pie);
}
template-page.php
<?php echo($new_pie); ?>
Thanks in advance.

Answer 1

I addressed this in a previous question of yours.
The 0 is being appended to the Ajax call because you need to die() after the echo.
echo $new_pie;
die();
This will stop the 0 from being appended.
As for the return of the data from the AJAX call, you need to do something with it, like append it to an element.
$('#elementID').append(data);
Which in this case, elementID is the ID of an element such as a DIV or P.
sidenote
There's no reason to use the following:
<script type="text/javascript">
var ajaxurl = '<?php echo admin_url('admin-ajax.php'); ?>';
</script>
Wordpress has created the javascript ajaxurl variable for you and has been doing so since WP 2.8.