One of the best ways to learn javascript or any other programming language is to practically use it. This is because hands-on experience stays with you longer than theoretical reading. You can start by developing a small side project of your own. Create this side project in the javascript framework you want to learn. Break down the project into smaller problems and try to solve the smaller problems, as it will help you in learning the bigger picture.
Pick a framework you want to learn. Check the online community for the same. Most of the frameworks are open source, so you can check the code repository on github. Also, search for the practical use for that framework as it will help in learning real-time usage.