Two reasons your code is not working.
1. Handle should be same i.e. ‘follow’ where as you are using the_follow and follow.
2. You have to execute statements in sequence i.e.(not sure)
a) Register Script
b) Localize Script
c) Enqueue Script
Ref: wp_localize_script
// Register the script
wp_register_script( 'follow', plugins_url('the-follow.js', __FILE__) );
// Localize the script with new data
$localize_array = array(
'ajax_url' => admin_url( 'admin-ajax.php' )
);
wp_localize_script( 'follow', 'postfollow', $localize_array );
// Enqueued script with localized data.
wp_enqueue_script( 'follow' );
Update 1:
Here is my folder structure
and here is the code, its working fine for me
