What should know senior front-end java developer? (e.g., JSON, JS, SQL, AWS)

Answer 1

I have a little doubt: Do you mean Java or Javascript?

If you mean Javascript, then CSS (Including some frameworks like Bootstrap and CSS preprocessors like LESS or SCSS), JS (React / Angular / Vue), JSON, JQuery and HTML.

If you mean Java, then the first thing to know is that the language works on the server side. And in that case (if you are programming both the frontend and the backend), you would be a full stack developer. Another thing that I would add in that case you should learn about Spring MVC, Play Framework, Grails, etc.

Answer 2

CSS, Html, JS (Angular JS, React, JQuery ). Json / XML.