How to add multiple classes to classlist.contains in javascript

I’m struggling to find a solution that allows me to update the following code to include additional classes. E.g. in addition to .section–bg1, I’d like to include .section–bg2. and .section–bg3.

For further context, here’s a Fiddle:

How can I include the red coloured background section (.section–bg2) in the JavaScript?

I’ve tried “el.classList.contains('section--bg1', 'section--bg2');” but that is not working. What am I missing?

// active section
if ( (sectionTop <= replaceItemBottom) && (sectionBottom > replaceItemTop)) {
  // check if current section has bg
  currentSection = el.classList.contains('section--bg1');

  // switch class depending on background image
  if ( currentSection ) { 
    replaceContainer[0].classList.remove('js-replace--reverse');
  } else {
    replaceContainer[0].classList.add('js-replace--reverse')
  }
}