https://flukeout.github.io/

https://js.coderslang.com/lecture/7

https://learngitbranching.js.org/

https://exercism.io/

https://sqlzoo.net/

https://checkio.org/

https://codecombat.com/

screeps.com

https://www.codecademy.com/

https://www.codingame.com/start

https://localcoding.us/

https://www.sqlhabit.com/

stepic.org

https://hyperskill.org/courses/65-javascript-core