w3schools, freecodingcamp, udemy, edx, microsoft learning, github, stack overflow
If you just go by online courses you will get bored with them pretty quick. The redundant usage of widget examples alone will make you contemplate euthanasia.
I always tell people it's best if you have an actual project or problem to solve and force yourself to use that language. After it's working, then try to make it better. Use github and Stack Overflow to see how others have handled problems similar to yours. If you have questions on a specific task / topic, you can always post a question here or on stack overflow.
After you've worked with a language for a while, I'd recommend getting a book on efficient coding patterns in that language (ie
Effective Python,
Python Cookbook,
Effective JavaScript), then books on any advanced topics you might be interested in.
Hope it helps, and good luck w/ the learning.