Merge .js files to load only "single merged maxi one"

You can use 2 differente templates. One for the development environment, and one for production.
E.g.:

template_dev.php:

PHP Code:

$this->load->view('template/header_dev');
$this->load->view($main_view);
$this->load->view('template/footer_dev'); 


template_prod.php:

PHP Code:

$this->load->view('template/header_prod');
$this->load->view($main_view);
$this->load->view('template/footer_prod'); 


In your controller, you do this:

PHP Code:

$data['main_view'] = 'the_view';
if (ENVIRONMENT == 'production') {
   $this->load->view('template/template_prod',$data);
}
else {
   $this->load->view('template/template_dev',$data);
} 


The header_prod.php file must load the merged js file. The header_dev.php file must load the js files separately.

Yes, thanks... but my issue is "how to auto-merge these files?". As I said, there are several enterprise platoform that do this kind of task beyond load different files