You need JavaScript, and though there are lots of libraries that make things simpler, you'll need a good understanding of JavaScript and preferably have a good

You need JavaScript, and though there are lots of libraries that make things simpler, you'll need a good understanding of JavaScript and preferably have a good understanding of the DOM as well. Libraries will help you with the DOM, but not a ton. They won't help you with the js. I suggest you start with a library, but make sure you understan what you're doing in terms of the DOM.