There are a lot of amazing courses to learn react js online.  The Internet is filled with amazing resources for javascript training, but here are 5 top recommendations - 

• Modern React with Redux (2020 Update) Udemy. 

• React 16 — The Complete Guide on Udemy.

• The Complete React Web Developer Course (with Redux) on Udemy.

• Advanced React and Redux: 2020 Edition on Udemy.

• React.js: Getting Started on Pluralsight.