• Frontend Handbook
• 2016-2017 Must-Know Web Dev Tech> (YouTube)
• So You Want To Be A Front-End Engineer (YouTube)
• Free Code Camp (a series of small exercises in myriad frontend technologies)
• Web Design Weekly

Tutorials:

• How to Learn Javascript (a compiled list of resources).
• Crockford on Javascript (YouTube playlist).
• W3 Schools Javascript
• Mozilla JS Guide
• Javascript.Info (tutorial)
• Javascript 30 (30 coding challenges in 30 days)

Books:

• You Don't Know JS
• Javascript Allongé
• Eloquent JavaScript

• Official Tutorial

• Awesome Flutter — links to projects, tutorials, articles.

• DART Programming Tutorial by TutorialsPoint.
• DART Cheat Sheet.