Beginner
Event Handling (eloquentjavascript.net)
Introduction to JavaScript (www.codecademy.com)
How JavaScript Works (blog.sessionstack.com)
Learn JavaScript (www.codecademy.com)
Learn JS (www.learn-js.org)
Javascript Dog (htmldog.com)
Front End Interview Handbook (github.com)
Treehouse - JavaScript Foundations (teamtreehouse.com)
Learn X in Y Minutes (learnxinyminutes.com)
Modern JavaScript for Ancient Developers (trackchanges.postlight.com)
Codecademy (www.codecademy.com)
Robust JavaScript (molily.de)
Eloquent Javascript (eloquentjavascript.net)
CoderMania (www.codermania.com)
What is AJAX? (www.youtube.com)
What is JavaScript? (www.youtube.com)
What is the DOM? (css-tricks.com)
JSON: What It Is, How It Works, & How to Use It (www.copterlabs.com)
Idiomatic JavaScript (github.com)
What's a JavaScript Library? (www.khanacademy.org)
Intermediate
Fight Code Game (fightcodegame.com)
JavaScript: The Right Way (jstherightway.org)
A Dive Into Plain Javascript (blog.adtile.me)
A re-introduction to JavaScript (developer.mozilla.org)
Superhero.js (superherojs.com)
Human Javascript (read.humanjavascript.com)
Code Wars (www.codewars.com)
Modular JavaScript (www.adequatelygood.com)
Advanced
Introduction to Object-Oriented JavaScript (developer.mozilla.org)
Learning Javascript Design Patterns (addyosmani.com)
Learning Advanced JavaScript (ejohn.org)