examples

html

DevTips, HTML5 Basics - Tags [video]
Codecademy, Make an Interactive Website.

html5 dom

DevTips, HTML5 Basics - The DOM [video].
Marijn Haverbeke, Eloquent JavaScript, The Document-Object Model (Chapter 13).

css

CSS-Tricks, CSS Guides.
Lea Verou, CSS Secrets
Dave Shea, CSS Zen Garden.
CSS-Tricks, Guide to Flexbox
nana, Ryan Yu, CSS selectors cheatsheet.

javascript

Marijn Haverbeke, Eloquent JavaScript Chapters 1, 2, 3, 4, 5, 6, 8.
David Flanagan, JavaScript: The Definitive Guide.
Richard Bovell, JavaScript Variable Scope and Hoisting Explained.
json.org, Introducing JSON.
DigitalOcean, Introduction to JSON.
JSHint, JSHint Code Quality Tool (available in most editor/IDEs).

event handlers

Marijn Haverbeke, Eloquent JavaScript, Handling Events (Chapter 14), HTTP (Chapter 17), Forms and Form Fields (Chapter 18).
QuirksMode, Introduction to Events, Event Order.
Javascript Kit, Understanding "event handlers" in JavaScript.

storage

W3Schools, HTML5 Local Storage.
Mosilla Web Docs, Window: localStorage property.

animation & graphics

W3Schools, CSS3 Animations.
Lea Verou, CSS Secrets, Section 14 + Chapter 8
Mozilla, animation.
W3Schools, HTML5 Canvas.
Abnin Sharma, 25 Ridiculously Impressive HTML5 Canvas Experiments.
Mozilla, Canvas tutorial

xpath

W3C, XML Path Language (XPath) Version 3.1.
devhints, XPath cheatsheet.