Although web components are still on the bleeding edge--barely supported in modern browsers--the technology is also moving extremely fast. This practical guide gets you up to speed on the concepts underlying W3C's emerging standard and shows you how to build custom, reusable HTML5 Web Components.
Regardless of your experience with libraries such as jQuery and Polymer, this book teaches JavaScript developers the DOM manipulations these libraries perform. You'll learn how to build a basic widget with vanilla JavaScript and then convert it into a web component that's semantic, declarative, encapsulated, consumable, and maintainable. With custom components, the Web can finally fulfill its potential as a natively extensible application platform. This book gets you in at the right time.
Understand core concepts (such as normal flow and positioning, and Z-index) for properly positioning, dragging, and resizing elements Explore UI concepts and patterns typically abstracted away by Dojo, jQuery UI, Kendo UI, and other libraries Dive into the W3C standard and convert your working widget example into a fully functioning web component Learn how to encapsulate, package, and deploy your web components with Google's Polymer framework
The book is pretty outdated. Most APIs referenced in the book have been deprecated or never made into the HTML spec. A lot of the book is about jQuery or Polymer and not about Web Components.
Though not perfect, I'd recommend Web Components in action as an alternative.
A book about Web Components where Polymer gets introduced around 75%. Weird :)
But it's not as bad as it seems, author is very thorough in presenting the need for componentization, problems you'll encounter & ways to achieve the target. If you know Backbone.js, it may be a bit boring and slow (part II, OMG ...), but things start to get interesting when author introduces Shadow DOM & Custom Elements.
What's more? Polymer chapter is a bit dated (0.5) & the testing part is very brief (but at least Karma got some love). Code samples are really nice (in whole book).