JavaScript is a must for Web Development, even if you plan on never using it. You may plan on using CoffeeScript, Dart or ClojureScript instead of JavaScript. Either way, it is important that you can understand what these languages are doing when they compile down to JavaScript.
If you are going to be building sites with Django, then JavaScript is a must. If you have the time then you could read a whole book on JavaScript, otherwise just read a 5 minute tutorial on JavaScript to get familiar with its capabilities and syntax. The best way to learn a language is to use it, JavaScript can be very frustrating because of how unpredictable it can be.
Code, Code, Code, and use Google to answer your questions. Good luck!