Filter WP's script_loader_src

fpl_wp_filter_script_loader.php

<?php

add_filter( 'script_loader_src', 'my_script_loader_filter' );
/**
* function for filter 'script_loader_src' it echo's a script-tag with it's src empty. the src is kept in data-src so javascript can put in the src-attr on a later moment. (e.g. after a cookie-check)
*
* @author Floris P. Lof
* @params String $src the current source of the scriptfile to be included
* @return Boolean false
*/
function my_script_loader_filter( $src ) {
   echo '<script type="text/javascript" src="" data-src="' . esc_url( $src ) . '"></script>' . PHP_EOL;
   return false; //unfortunately this also leaves you with an extra blank script-tag in your DOM :-(	
}