Can't get jQuery to enqueue into post edit script

Question

In the code below, unless I hardcode a reference to the jQuery library, my jQuery bits on the page do not work. What's wrong with the enqueue method I'm trying to use?

In functions.php:

if(is_admin())
{

/* LOAD ADMIN SCRIPTS
**********************************/
require_once(TEMPLATEPATH . '/functions_private.php');

}

In functions_private.php:

if( 'post.php' == $pagenow )
{

    add_action('admin_print_scripts', 'my_load_ui_script');

    function my_load_ui_script()
    {
    wp_enqueue_script('jquery');
    ?>
        <!--<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>-->
        <script>
        if(typeof jQuery!="undefined"){
            alert("You have jQuery loaded");//WILL NOT FIRE UNLESS I HARDCODE JQUERY INCLUDE
        }           

        jQuery(document).ready(function()
        {
        //jquery bits go here
        }

    }//END FUNCTION 

}//END IF

Answer 1

Use the admin_enqueue_scripts hook to add your own custom script. Put it in an external file, and use wp_localize_script to pass any data from php to javascript. jQuery is already used on the admin side, adding a script tag sourcing it from google will break things.

function wpa80418_admin_enqueue( $hook ) {
    if( 'post.php' != $hook )
        return;
    wp_enqueue_script(
        'my_custom_script',
        get_template_directory_uri() . '/js/myscript.js',
        array('jquery')
    );
}
add_action( 'admin_enqueue_scripts', 'wpa80418_admin_enqueue' );

Answer 2

WordPress jQuery does not support $ by default.

First Add jQuery.

function my_scripts_method() {
    wp_enqueue_script(array('jquery'));
}
add_action('admin_enqueue_scripts', 'my_scripts_method');

replace this code:

jQuery(document).ready(function()
        {
        //jquery bits go here
        }

with:

jQuery(document).ready(function($) {
    // $() will work as an alias for jQuery() inside of this function
});

Answer 3

The admin_footer hook proves to be the right hook for Scott B's code. However, it is generally recommended to enqueue scripts (and declare their jQuery dependency) as described in the answer of @Milo

Answer 4

Event listeners

Simple:

• The script executes immediately when you run it, as it doesn't use any javascript event listener like waiting until the DOM or the window or whatever loaded.
• The enqueued script (jQuery) will be rendered on its appropriate hooks: In the head or - if enqueued mid-page - in the footer.

Therefore jQuery is simply not available when you call it.