[WordPress] WordPress Ajax Responses in JSON

00-wp-send-json-error.php

<?php

// We're going to try to look up a user by his/her email address.
$user = get_user_by( 'email', 'tom@mattreport.com');

/* Next, if the $user object exists, we'll respond with a JSON-based
 * response that includes the user's ID. Since this email address
 * does *not* exist, we're going to response with an error.
 */ 
if ( false !== $user ) {
  // Removed since it's already been covered.
} else {
  
  wp_send_json_error(
    new WP_Error( '-1', 'The specified user does not have an account.' )
  );
}

00-wp-send-json-success.php

<?php

// We're going to try to look up a user by his/her email address.
$user = get_user_by( 'email', 'tom@tommcfarlin.com');

/* Next, if the $user object exists, we'll respond with a JSON-based
 * response that includes the user's ID.
 */ 
if ( false !== $user ) {
  
  wp_send_json_success(
    array( 'User ID' => get_user_by_id( 'id', $user->ID ) )
  );
}