To understand the concepts and code in this book, you don't need much more than a JavaScript environment and a text editor. To be honest, I even developed some of the examples working fully online, with tools such as JSFiddle (at https://jsfiddle.net/) or the like, with absolutely nothing else.
However, you will need some experience with the latest version of JavaScript, because it includes several features that help writing more concise and compact code. We will frequently include pointers to online documentation, such as the documentation available on the MDN (Mozilla Development Network at https://developer.mozilla.org/) to help you get more in-depth knowledge.