Try doing things hands on, take a project and work it out, find examples on other sites.
W3Schools is a nice reference with editable examples. Use Stackoverflow for the more serious questions.
Javascript is fun to learn. Find sites you like and try to copy the functionality, tweak and learn along the way.
I used to have a book, Javascript in ten minutes, it had some examples and used it as reference on my desk for years, but that was over 15 years ago
Google, W3S and Stack are your friends in this one.. And JQuery