This part of the documentation is not meant for end users of Coppermine, but only for developers. There is no support for this section, it comes as-is.
// This line of code will include displayimage.js file js_include('js/displayimage.js');
<?php $foo = 'bar'; set_js_var('php_foo', $foo); ?>
Keep in i18n in mind, especially for the strings passed from language files: be particularly mindfull on properly escaping single quotes (apostrophes) that may reside in other languages than the one you're testing with.
The advantage of this method is that jquery will take care of triggering the autostart functions - there can be several of those "document ready" constructs, even in different .js files.