Separei 3 dos melhores conteúdos que já vi sobre JS estão aqui:

• Eloquent Javascript (Livro completo de JS)
• Clean Code JS (Como escrever código bem feito)
• Idiomatic JS (Como escrever código consistente)

Com esses conteúdos você vai conseguir avançar muito como desenvolvedor JS.

Recursos úteis

Caso você queira se afogar em conteúdo, a lista abaixo contém uma série de recursos relacionados a Javascript em inglês, você pode acessar a referência original da curadoria da lista aqui

Documentation

• DevDocs is an all-in-one API documentation reader with a fast, organized, and consistent interface.
• dexy is a free-form literate documentation tool for writing any kind of technical document incorporating code.
• docco is a quick-and-dirty, hundred-line-long, literate-programming-style documentation generator.
• styledocco generates documentation and style guide documents from your stylesheets.
• Ronn builds manuals. It converts simple, human readable textfiles to roff for terminal display, and also to HTML for the web.
• dox is a JavaScript documentation generator written with node. Dox no longer generates an opinionated structure or style for your docs, it simply gives you a JSON representation, allowing you to use markdown and JSDoc-style tags.
• jsdox is a JSDoc3 to Markdown documentation generator.
• ESDoc is a good documentation generator for JavaScript.
• YUIDoc is a Node.js application that generates API documentation from comments in source, using a syntax similar to tools like Javadoc and Doxygen.
• coddoc is a jsdoc parsing library. Coddoc is different in that it is easily extensible by allowing users to add tag and code parsers through the use of coddoc.addTagHandler and coddoc.addCodeHandler. coddoc also parses source code to be used in APIs.
• sphinx a tool that makes it easy to create intelligent and beautiful documentation
• Using JSDoc
• Beautiful docs is a documentation viewer based on markdown files.
• documentation.js - API documentation generator with support for ES2015+ and flow annotation.
• jsduck - API documentation generator made for Sencha JavaScript frameworks, but can be used for other frameworks too.
• codecrumbs is a visual tool for learning and documenting a codebase by putting breadcrumbs in source code.

Editors

• ace - Ace (Ajax.org Cloud9 Editor).
• CodeMirror - In-browser code editor.
• esprima - ECMAScript parsing infrastructure for multipurpose analysis.
• quill - A cross browser rich text editor with an API.
• medium-editor - Medium.com WYSIWYG editor clone.
• pen - enjoy live editing (+markdown).
• jquery-notebook - A simple, clean and elegant text editor. Inspired by the awesomeness of Medium.
• bootstrap-wysiwyg - Tiny bootstrap-compatible WYSIWYG rich text editor.
• ckeditor-releases - The best web text editor for everyone.
• editor - A markdown editor. still on development.
• EpicEditor - An embeddable JavaScript Markdown editor with split fullscreen editing, live previewing, automatic draft saving, offline support, and more.
• jsoneditor - A web-based tool to view, edit and format JSON.
• vim.js - JavaScript port of Vim with a persistent ~/.vimrc.
• Squire - HTML5 rich text editor.
• TinyMCE - The JavaScript Rich Text editor.
• trix - A rich text editor for everyday writing. By Basecamp.
• Trumbowyg - A lightweight and amazing WYSIWYG JavaScript editor.
• Draft.js - A React framework for building text editors.
• bootstrap-wysihtml5 - Simple, beautiful wysiwyg editor
• wysihtml5 - Open source rich text editor based on HTML5 and the progressive-enhancement approach. Uses a sophisticated security concept and aims to generate fully valid HTML5 markup by preventing unmaintainable tag soups and inline styles.
• raptor-editor - Raptor, an HTML5 WYSIWYG content editor!
• popline - Popline is an HTML5 Rich-Text-Editor Toolbar.
• Summernote - Super simple WYSIWYG editor.

Podcasts

• JavaScript Air - The live video broadcast podcast all about JavaScript and the Web platform.
• Web of Tomorrow - Podcast about JavaScript for beginners.
• JavaScript Jabber - A weekly podcast about JavaScript, including Node.js, Front-End Technologies, Careers, Teams and more.

Worth Reading

• You Don't Know JS - Possibly the best book written on modern JavaScript, completely readable online for free, or can be bought to support the author.
• braziljs/js-the-right-way - An easy-to-read, quick reference for JS best practices, accepted coding standards, and links around the Web.
• JSbooks - Directory of free JavaScript ebooks.
• Superhero.js - A collection of resources about creating, testing and maintaining a large JavaScript code base.
• SJSJ - Simplified JavaScript Jargon is a community-driven attempt at explaining the loads of buzzwords making the current JavaScript ecosystem in a few simple words.
• How to Write an Open Source JavaScript Library - A comprehensive guide through a set of steps to publish a JavaScript open source library.
• JavaScript Tutorials - Learn Javascript online from a diverse range of user ranked online tutorials.
• Functional-Light JavaScript - Pragmatic, balanced FP in JavaScript.
• Clean Code JavaScript - Clean Code concepts adapted for JavaScript.

ES6

• es6features - Overview of ECMAScript 6 features.
• es6-features - ECMAScript 6: Feature Overview & Comparison.
• es6-cheatsheet - ES2015 [ES6] cheatsheet containing tips, tricks, best practices and code snippets.
• ECMAScript 6 compatibility table - Compatibility tables for all ECMAScript 6 features on a variety of environments.
• Babel (Formerly 6to5) - Turn ES6+ code into vanilla ES5 with no runtime.
• Traceur compiler - ES6 features > ES5. Includes classes, generators, promises, destructuring patterns, default parameters & more.

Boilerplates

• html5-boilerplate - A professional front-end template for building fast, robust, and adaptable web apps or sites.
• mobile-boilerplate - A front-end template that helps you build fast, modern mobile web apps.
• webplate - An awesome front-end framework that lets you stay focused on building your site or app while remaining really easy to use.
• Cerberus - A few simple, but solid patterns for responsive HTML emails. Even in Outlook.
• full-page-intro-and-navigation - An intro page with a full width background image, a bold animated menu and an iOS-like blurred effect behind the navigation.
• Fluid-Squares - A fluid grid of square units.
• Mobile-First-RWD - An example of a mobile-first responsive web design.
• this-is-responsive - This Is Responsive.
• npm run-scripts Task automation with NPM run-scripts.

Articles and Posts

• The JavaScript that you should know - Article about concepts of JavaScript Functional.
• How JavaScript works - A series of articles about the building blocks of JavaScript.