I'm an ASP.NET developer and I won't get any job because of my JavaScript skills.

I started reading about JavaScript in articles and tutorials but I still didn't pick a book to read. But what I'm trying to understand. For example If you want to test your ASP.NET skills you firstly start learning the basics from a book, course, etc.

And to increase my knowledge and experience, I would build a website of any given idea and start to face troubles and learn as I go. but what can I do with JavaScript! .. how am I supposed to know how good I am at it !?

First Things First: I'm sorry guys, I've been facing some troubles to Comment or UpVote on the website but It's finally over, so Thanks everybody for your help =)