This paid membership site provides tons of short video lessons for front-end developers.
The quality differs a bit. Some courses are quite thorough, but some just scratch the surface.
For example, Up and Running with TypeScript only offered a glimpse of what TypeScript can offer.
The Cycle.js Fundamentals course by framework creator André Staltz gives you a good understanding of what Cycle.js has to offer and how to use it.
Egghead.io also comes with lots of free resources which they call Community Resources.
There are also some free courses for React, i.e. Kent C. Dodds’s The Beginner’s Guide to React.
I encourage you to check this site out, and at least take a glimpse at the free courses.