Does hidden content such asSlideshowsClick to expandTabs ModalsOr any content that is dynamically hidden using CSS or JS and shown to the user on click or when user does XMany sites have such UX, and I was wondering if the hidden content adds any value to SEO since the content is initially hidden to the user. 
How do search engines treat hidden content such as tabs and slideshows?
seo;hidden text;ux