How to run webpack dev server with different settings?

Question

webpack

I have music playing in my project and transitions between screens are in the form of gifs with pictures for 2-3 seconds. Is it possible to create two modes of devserver operation? Ie one mode which will ignore certain functions and styles? If so, where can I read about it. For example, I want this:
1 mod standard

//another script 

const  preloader = ( ) => {
   // code 
}
preloader()

1 launch mode in which the entire application starts without changes.
And the second launch mode in which the preloader function is not executed. And it is desirable to do this with styles (sass)

<code lang="javascript">

//another script 

const  preloader = ( ) => {
   // code 
}
//preloader()
</code>