How many libraries and frameworks on JavaScripts should I know?(list them)

Answer 1

You are not mandatory to use/know JS libraries and frameworks...
However, if you need some specific function already existing and you don't want to reivent the wheel, so search which libraries/frameworks provide tools related to your needs, and go learning and using it ^^

Answer 2

For me, I only need React.js is good enough to build lots of web applications.