Ajax handlers for WordPress

wp-ajax_handlers.php

<?php 
add_action( 'wp_ajax_action_slug', 'action_slug' );
add_action( 'wp_ajax_nopriv_action_slug', 'action_slug' );

function action_slug() {
  
  check_ajax_referer('form_nonce');
  
  $errors = array(); // Array to hold validation errors
  $data   = array(); // Array to pass back data
  
  // Validation logic if any...
  
  // return a response
  if( ! empty($errors) ) {
    
    // if there are errors, return those errors
    $data['success'] = false;
    $data['errors']  = $errors;
  }
  else {
    
    // if there are no errors, process the form and return a message
    
    // form processing logic
    
    $data['success'] = true;
    $data['message'] = 'Success';
  }
  
  echo json_encode($data);
  wp_die();
}