I am struggling to get my ajax request to work. It fails when I fire my $ajax and I get this error...

Uncaught ReferenceError: feature_ajax is not defined

This is my functions.php

// load our frontend modifiers
require_once(__DIR__ . '/lib/Frontend.lib.php');

This is my Frontend.lib.php class php...

class Frontend

    /** frontend constructor */
    public function __construct()

        // enqueue our scripts
        add_action('wp_enqueue_scripts', array($this, 'action_wp_enqueue_scripts'));

        // add out ajax actions


    /** frontend enqueued scripts */
    public function action_wp_enqueue_scripts()

        // localize admin ajax
        wp_localize_script('ajax-actions', 'ajax_actions', array(
            'ajaxurl' => admin_url( 'admin-ajax.php' )

        // enqueue scripts


    /** ajax actions */
    public function ajax_actions()

        // admin field postdata ajax actions
        add_action('wp_ajax_field_postdata', [__CLASS__, 'field_postdata']);

        // public field postdata ajax actions
        add_action('wp_ajax_nopriv_field_postdata', [__CLASS__, 'field_postdata']);


    // Field Post Data
    public static function field_postdata()
        global $post;
        $post_id = ($_REQUEST['id']);

            $post = get_post($post_id);



new Frontend();

When I fire the $ajax script below, this is when I get the error feature_ajax is not defined.

But it is defined in the code above.

This script below is my theme-min.js file

// load feature post data
    cache: false,
    timeout: 8000,
    url: ajax_actions.ajaxurl,
    type: 'POST',
    data: {
        action: 'field_postdata',
        id: post_id
    success: function (data) {

Any help in understanding what i'm doing wrong would be great.


Updated Fixed Code

So what I changed to make this work. I was already enqueuing my main-min.js file, so I combined my wp_localize_script using the same handle as my enqueued javascript and it worked.

// register js in footer
$filename = get_template_directory_uri() . '/assets/scripts/main-min.js';
wp_register_script('main-js', $filename, array(), rand(), true);

// localize theme-js ajax actions
wp_localize_script('main-js', 'ajax_actions', array(
    'ajaxurl' => admin_url( 'admin-ajax.php' )

// enqueue required scripts
  • Have you considered using the REST API instead? It's much easier to debug, and more straightforward to register – Tom J Nowell Oct 9 '18 at 1:57

To successfully add variable to the window object via wp_localize_script you need to properly invoke three functions in the following sequence:

  1. wp_register_script

  2. wp_localize_script

  3. wp_enqueue_script

In your case you're missing the wp_register_script. In case someone experiences the same issue, follow the code procedures below.


    function my_theme_wp_enqueue_scripts() {
        $handle = 'my_handle';

        // Register the script
        wp_register_script($handle, '/path/to/my_script.js');

        // Localize the script with a new data
        wp_localize_script($handle, 'object_name', [
            'ajax_url' => admin_url('admin-ajax.php')

        // Enqueue the script
    add_action('wp_enqueue_scripts', 'my_theme_wp_enqueue_scripts');

Then, you can access the localized object in Javascript

var ajax_url = object_name.ajax_url;

Change the $handle variable content as well as the object_name in PHP that makes sense to your application.

  • Ahhh i see i was already wp_register_script('theme-js', ...) so i've just done this now wp_localize_script('theme-js', ... ) and it works now thank you dude – joshmoto Oct 9 '18 at 2:32

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