WordPress.org

How should I code the URL inside the wp_js() function

All the URLs must be relative to the current theme.

For example if your theme is default and you have javascript file called file.js inside this theme.

<script src="<?php wp_js('file.js'); ?>" type="text/javascript"></script>

If you had a file inside another folder within the current theme folder. For example, theme/default/javascript

<script src="<?php wp_js('javascript/file.js'); ?>" type="text/javascript"></script>

Can I suggest an feature for the plugin?

Of course, visit WP JS Home Page

Are you available for hire?

Yes I am, visit my services page to find out more.