Function: is_single

Use a Custom Field to Add to the

I needed a very simple way to custom styles or scripts to the <head>, and I didn’t really want to customize the theme.

add_action( 'wp_head', 'wp_head_custom_field' );
function wp_head_custom_field() {
    if ( is_single() ) {
        global $post;
        $html = get_post_meta( $post->ID, 'wp_head', true );
        echo $html;
    }
}

With this, I just needed to add my pre-formatted javascript or css to a custom field called ‘wp_head’ and it would then be added to the <head> just like I needed. I added the is_single() as a precaution.