Once you get a grip on what the language is capable of and how to use it, then you can understand how the frameworks work and why they save time / make life easier (or harder).
I once worked with a programmer that learned Laravel without actually learning PHP. That's great - he could jump into Laravel projects, but when it came time for him to help on anything custom or WP sites; he was completely lost. He also had no idea how or why Laravel worked; just that he memorized x snippets of code and they produced a result.
It'll make you a better programmer in the long run.
MDN Javascript resources: https://developer.mozilla.org/en-US/docs/Web/JavaScript
Before starting the tutorials, take some time to learn what's available in the Firefox developer tools. You won't need most of them at first, but knowing what's available will help as you gain experience.
The two developer tools you'll probably use most when leaning are the Scratchpad (https://developer.mozilla.org/en-US/docs/Tools/Scratchpad) and Console (https://developer.mozilla.org/en-US/docs/Tools/Web_Console)
https://jsfiddle.net/ & http://jshint.com/ will also be very useful while learning JS
I haven't taken any but Udacity has some javascript courses (https://www.udacity.com/courses/all), just tick the "Javascript" checkbox under "Technology" in the left menu
Some additional resources:
https://developer.chrome.com/devtools
https://msdn.microsoft.com/library/bg182326(v=vs.85)
https://msdn.microsoft.com/en-us/library/d1et7k7c(v=vs.94).a...
http://www.ecma-international.org/ecma-262/6.0/index.html
https://github.com/getify/You-Dont-Know-JS
https://addyosmani.com/resources/essentialjsdesignpatterns/b...
Dated but still worth watching:
https://www.youtube.com/watch?v=hQVTIJBZook
https://www.youtube.com/watch?v=bo36MrBfTk4
edit: added addl. resources