The article "A Study Plan to Cure Javascript Fatigue" (
https://medium.freecodecamp.com/a-study-plan-to-cure-javascr... ) is a great place to start. It gives an excellent series of steps for tackling modern Javascript concepts one piece at a time: Javascript, React, ES6, and state management. There's also a "Front-End Study Guide" based on that article that's very good, at
https://github.com/grab/front-end-guide .