How to enqueue script based on post category?

Inside your theme’s functions.php add something like this:

function my_conditional_enqueue_script() {
    global $post;
    if (is_single($post->ID) && in_category('mouse', $post->ID)) {
        wp_enqueue_script('mousescript');
    }
}
add_action('wp_enqueue_scripts', 'my_conditional_enqueue_script');

Also, make sure you use wp_register_script before you attempt to enqueue.