I added the following code to my functions.php:

if(!function_exists('bi_frontend_scripts')) {
    function bi_frontend_scripts() {
        wp_enqueue_script('jquery');
        // I originally wanted to do:
        wp_enqueue_script('jQuery.bxSlider', get_bloginfo('template_url').'/scripts/jquery.bxslider/jquery.bxslider.min.js', array('jquery'));
    }
}
add_action('wp_enqueue_scripts', 'bi_frontend_scripts');

But apparently neither of the scripts is being enqueued. I didn't get what my problem was, so I added this script to find out if the hook is called:

function aal_handler() {
    static $list = array();
    // exclude certain actions:
    $exclude = array('gettext', 'gettext_with_context');

    $action = current_filter();

    if(!in_array($action, $exclude)) {
        $list[] = $action;
    }
    // shutdown is the last action
    if ('shutdown' == $action) {
        print '<pre>' . implode( "\n", $list ) . '</pre>';
    }
}
add_action('all', 'aal_handler', 99999, 99);

And in the list wp_enqueue_scripts does not appear. So why the hook is not called?!

I added the following code to my functions.php:

if(!function_exists('bi_frontend_scripts')) {
    function bi_frontend_scripts() {
        wp_enqueue_script('jquery');
        // I originally wanted to do:
        wp_enqueue_script('jQuery.bxSlider', get_bloginfo('template_url').'/scripts/jquery.bxslider/jquery.bxslider.min.js', array('jquery'));
    }
}
add_action('wp_enqueue_scripts', 'bi_frontend_scripts');

But apparently neither of the scripts is being enqueued. I didn't get what my problem was, so I added this script to find out if the hook is called:

function aal_handler() {
    static $list = array();
    // exclude certain actions:
    $exclude = array('gettext', 'gettext_with_context');

    $action = current_filter();

    if(!in_array($action, $exclude)) {
        $list[] = $action;
    }
    // shutdown is the last action
    if ('shutdown' == $action) {
        print '<pre>' . implode( "\n", $list ) . '</pre>';
    }
}
add_action('all', 'aal_handler', 99999, 99);

And in the list wp_enqueue_scripts does not appear. So why the hook is not called?!

• jquery
• wp-enqueue-script
• front-end

• Maybe bi_frontend_scripts() was defined previously and therefore doesn't pass the check for its non-existence? – kaiser Commented Mar 16, 2014 at 15:15
• No, I already took this into account – Julian F. Weinert Commented Mar 16, 2014 at 15:16

3 Answers 3

Your code is correct, though I would not add the callback if the function name has already been used. If someone else has used the name you don't know what you might be adding.

if(!function_exists('bi_frontend_scripts')) {
    function bi_frontend_scripts() {
        wp_enqueue_script('jquery');
        // I originally wanted to do:
        wp_enqueue_script('jQuery.bxSlider', get_bloginfo('template_url').'/scripts/jquery.bxslider/jquery.bxslider.min.js', array('jquery'));
    }
    add_action('wp_enqueue_scripts', 'bi_frontend_scripts');
}

I also tested your "hook dump" function-- aal_handler()-- and that works. wp_enqueue_scripts is part of the output.

I have to conclude that there is something wrong with the theme. wp_enqueue_scripts is hooked to wp_head, which fires in the wp_head() function. The most obvious possibility is that your theme is not using wp_head() correctly, or at all. Another distant possibility is that something has removed your callback-- for example, with:

remove_all_filters('wp_enqueue_scripts');

For anyone getting this problem in an admin page, use the admin_enqueue_scripts hook instead of the wp_enqueue_scripts hook.

Documentation here.

I am here again with a lot of information for you so that you understand how things work with wp_enqueue_scripts.

You need to know the priority order for the wp_enqueue_scripts. See hook order below:

1. muplugins_loaded
2. registered_taxonomy
3. registered_post_type
4. plugins_loaded
5. sanitize_comment_cookies
6. setup_theme
7. load_textdomain
8. after_setup_theme
9. auth_cookie_malformed
10. auth_cookie_valid
11. set_current_user
12. init
13. widgets_init
14. register_sidebar
15. wp_register_sidebar_widget
16. wp_default_scripts
17. wp_default_stypes
18. admin_bar_init
19. add_admin_bar_menus
20. wp_loaded
21. parse_request
22. send_headers
23. parse_query
24. pre_get_posts
25. posts_selection
26. wp
27. template_redirect
28. get_header
29. wp_head
30. wp_enqueue_scripts
31. wp_print_styles
32. wp_print_scripts

...and so on.

So you see you can add it in the init hook and doing so it will be called as high priority than below the listing.

If your files are not loading you could use a higher priority hook.

If your wp_enqueue_script is not being called, you can use this simple trick to get it working for your theme or plugin.

<?php

if(!function_exists('bi_frontend_scripts')) {
    function bi_frontend_scripts() {
        wp_enqueue_script('jquery');
        // I originally wanted to do:
        wp_enqueue_script('jQuery.bxSlider', get_bloginfo('template_url').'/scripts/jquery.bxslider/jquery.bxslider.min.js', array('jquery'));
    }

    add_action( 'init', 'bi_frontend_scripts' );
}


?>