Adding <script src="wp-content/file/script.js"></ script> is not a clean way to load your JS files because this is not a relative URL and when you active your child theme probably your theme will not load your JS file, the solution is :
<script src="<?php echo get_stylesheet_directory_uri(); ?>/js/script.js"></script>
You need to add this to your footer.php file in your theme directory wp-content\themes\your_theme\footer.php
but the best way is to use WP hooks to include your scripts, first you need to register them using
wp_register_script( 'my_script_name', get_template_directory_uri(). '/js/script.js' );
then simply load them
wp_enqueue_script( 'my_script_name' );
Don't try to register and enqueue your scripts directly in your footer.php file, instead create a method in your functions.php template file then load your scripts using
add_action( 'wp_enqueue_scripts', 'my_scripts_method' );
Note: To enqueue your scripts to the footer you need to set $in_footer parameter to true.
Checkout wp_enqueue_script for more information.