How to set images path on libraries JS file in Drupal 8? I would like your kind help to point the correct path of images from JS.
I'm trying to change a DIV background using CSS and JS. Quite simple, right?
Well, not for me in Drupal 8. 

My div loads the background defined in the CSS (my_module.libraries.yml)
The JS also works for changing positions of the layers (or DIVs, sorry, I'm from the Netscape times, old school). 
But it doesn't work for setting the background because cannot find the images.
That means that there is no problems regarding routing neither configuration of the module.

So, the question is: How can I set the path for the CSS images in the JS libraries? 

Here goes some codes:

My_module.libraries.yml


box-simulador:
  version: 1.x
  css:
    theme:
      css/box-simulador.css: {}
  js:
    js/box-simulador.js: {}


Excert from the CSS file


#SimHolder {
    background: url(img/pillow.png) left top no-repeat; /* &lt;&lt; WORKS FINE! */


Excert from the JS file


function setTowel() {
 document.getElementById('SimHolder').style.backgroundImage='url(img/towel.png)'; // DOESNT WORK :(
 document.getElementById('textHolder').style.top='30%'; // IT WORKS! 


I'm sure the answer would be quite simple ;)
Thanks in advance!
Weel, I found s solution, quite simple: just use {{directory}} on the template. ;)