I'm in the same position as you. I realised I was still writing spaghetti code that relied heavily on DOM manipulation with Jquery. I am currently learning how the language has evolved and the following has been helpful —

1. https://javascript.info/

2. https://www.youtube.com/watch?v=JxAXlJEmNMg (videos, watch all of them)

3. http://jstherightway.org/

4. http://eloquentjavascript.net/

Hope this helps :)