So i'm trying to make a follow button in wordpress where users can press a button that allows them to follow an author they like. (No, i'm not interested in buddypress)

What i've done so far is use the code from Jon Masterson's Post Like System for WordPress http://hofmannsven.com/2013/laboratory/wordpress-post-like-system/ which pretty much adds a +1 update_post_meta when ever a user likes the post.

The problem i've ran into, is if you go all the way to the bottom you'll see that the like system uses update_post_meta to give a +1 to the count of the post meta, which is exactly what I need for the follow button. The problem is that I can't find a function update_author_meta to store the ++$author_follow_count for that specific author. If you know of a way for me to store and update the follow count for a specific author, or point me in the right direction, it would be greatly appreciated.

<?php
function follow_scripts() {
wp_localize_script( 'jk_like_post', 'ajax_var', array(
    'url' => admin_url( 'admin-ajax.php' ),
    'nonce' => wp_create_nonce( 'ajax-nonce' )
        )
    );
}
add_action( 'init', 'follow_scripts' );

/**
* (2) Save follow data
*/
add_action( 'wp_ajax_nopriv_jk-author-follow', 'jk_author_follow' );
add_action( 'wp_ajax_jk-author-follow', 'jk_author_follow' );
function jk_author_follow() {
   $nonce = $_POST['nonce'];
if ( ! wp_verify_nonce( $nonce, 'ajax-nonce' ) )
        die ( 'Nope!' );

if ( isset( $_POST['jk_author_follow'] ) ) {
    
    $author_id = $_POST['author_id']; // author id
    $author_follow_count = get_author_meta( $author_id,        "_author_follow_count", true ); // author follow count
    
    if ( function_exists ( 'wp_cache_post_change' ) ) { // invalidate WP Super Cache if exists
                $GLOBALS["super_cache_enabled"]=1;
                wp_cache_post_change( $post_id );
    }
    
    if ( is_user_logged_in() ) { // user is logged in
        $user_id = get_current_user_id(); // current user
        $meta_AUTHORS = get_user_option( "_followed_authors", $user_id ); // author ids from user meta
        $meta_USERS = get_author_meta( $author_id, "_user_followed" ); //user ids from author meta
        $followed_AUTHORS = NULL; // setup array variable
        $followed_USERS = NULL; // setup array variable
        
        if ( count( $meta_Authors ) !=0 ) { // meta exists, set up values
            $followed_AUTHORS = $meta_AUTHORS;
        }
        
        if ( !is_array( $followed_AUTHORS ) )  // make array just in case
            $followed_AUTHORS = array();
            
        if ( count( $meta_USERS ) !=0 ) { // meta exists, set up values
            $followed_USERS = $meta_USERS[0];
        }
        
        if ( !is_array( $followed_USERS ) ) //make an array just in case
            $followed_USERS = array();
        
        $followed_AUTHORS['author-'.$author_id, "_user_followed"] = $author_id; // Add author id to user meta array
        $followed_USERS['user-'.$user_id] = $user_id; // add user id to author meta array
        $user_follows = count( $followed_AUTHORS ); // count user follows
        
 // *** Where the snag is ****
        if ( !AlreadyFollowed( $author_id ) ) { // follow the author
            update_post_meta( $author_id, "_user_followed", $followed_USERS ); // Add user ID to author meta
            update_post_meta( $author_id, "_author_follow_count", ++$author_follow_count ); // +1 count author meta
            update_user_option( $user_id, "_followed_authors", $followed_Authors ); // Add author ID to user meta
            update_user_option( $author_id, "_author_follow_count", $user_follows ); // +1 count user meta
            echo $author_follow_count; // update count on front end

Update

Okay I fiddled with (4) and used your code, am I on the right track? Also where do I place the die for the ajax? Thanks

/**
* (1) Enqueue scripts for follow system
*/
function follow_scripts() {
wp_enqueue_script( 'jk_follow_post', get_template_directory_uri().'/js/post-   like.min.js', array('jquery'), '1.0', 1 );
 wp_localize_script( 'jk_like_post', 'ajax_var', array(
    'url' => admin_url( 'admin-ajax.php' ),
    'nonce' => wp_create_nonce( 'ajax-nonce' )
        )
    );
}
/**
* (2) Save follow data
*/
add_action( 'wp_ajax_nopriv_jk-author-follow', 'jk_author_follow' );
add_action( 'wp_ajax_jk-author-follow', 'jk_author_follow' );
function jk_author_follow() {
$nonce = $_POST['nonce'];
if ( ! wp_verify_nonce( $nonce, 'ajax-nonce' ) )
        die ( 'Nope!' );

if ( isset( $_POST['jk_author_follow'] ) ) {
    
    $author_id = $_POST['author_id']; // author id
    
    
    if ( is_user_logged_in() ) { // user is logged in
        $user_id = get_current_user_id(); // current user
        
        // create the term if it doesn't exist
        if ( !term_exists( $author_id, 'wpse_180398_followers' ) ) {
            wp_insert_term( $author_id, 'wpse_180398_followers' );
        }

        // follow the user, note the last argument is true
        $term_ids = wp_set_object_terms( $user_id, $author_id, 'wpse_180398_followers', true );

        if ( is_wp_error( $term_ids ) ) {
            // There was an error somewhere and the terms couldn't be set.
            echo "error";
        } else {
            // Success!
        }
    }
}
}
/**
 * (3) Test if user already liked post
 */
function AlreadyFollowed( $author_id ) { // test if user is following author
$user_id = get_current_user_id(); // current user
$author_id = $_POST['author_id']; // author id
if ( is_user_logged_in() ) { // user is logged in
    if ( has_term( $author_id, 'wpse_180398_followers', $user_id ) ) {
        // user_id is following author_id!
    }
}
}
/**
  * (4) Front end button
*/
function getFollowLink( $author_id ) {
$author_id = $_POST['author_id']; // author id
$user_id = get_current_user_id(); // current user
if ( has_term( $author_id, 'wpse_180398_followers', $user_id ) ) {
    $following = esc_attr( 'Following' );
}
else{
    $following = esc_attr( 'Follow' );
}
$output = '<a class="follow-button '.$following.'" data-author="'.$author_id.'"</a>';
}
/**
 * (5) Add a shortcode to your posts instead
 * type [jkfollower] in your post to output the button
*/
function jk_follow_shortcode() {
return getFollowLink( get_the_ID() );
}
add_shortcode('jkfollower', 'jk_follow_shortcode');