To learn any programming language, you should have some knowledge about programming. You need to learn Javascript to be a Javascript developer. If you are new to the programming world, you need to have a solid understanding of the basics of coding.
If you've already been exposed to programming / coding (in any language), it's easy to learn Javascript. Start with basic coding. Functions, loops, conditional expressions, etc. The basics of coding are important for a JS developer.
Start a simple project that will help you learn JS concepts. You need to write code to understand how it works, to change the code, and to enrich it as you go.
Do not start with any JS framework. Use them only if you have important information about JS, use them if necessary.
'You don't know JS' is a great book series written by Simpson. Covering basic information about advanced JS issues. This is the best reference for getting information on Javascript.
