To program in js you do not need much: just a browser and a text editor. Regarding the browser, you might already have one, so you can choose to use any one you like, but here is a list of the ones I believe are the best for this course:
Talking about the text editor, again, they are all good, but I would suggest downloading one with syntax highlighting, like one of these below:
Once you have downloaded and installed the text editor and the browser of your choosing, we are ready to get coding!