The document discusses using Zepto.js, a lightweight jQuery-compatible JavaScript library, to create a mobile version of a website called ingatlan.com. It notes that Zepto.js is much smaller than jQuery and handles touch events well for mobile. However, early versions of Zepto.js lacked documentation and did not fully replicate jQuery's functionality. But more recently, Zepto.js has improved with new releases, adding documentation and becoming more compatible with jQuery. Additionally, other mobile JavaScript libraries have emerged as alternatives to Zepto.js and jQuery.