A fieldbook for polyfill developers, the book will share principles and guidelines for building polyfills that developers can rely on. Once the guidelines have been established, the book will shift to an in-depth walkthrough of building a real-life, reasonably complex polyfill, by example (an HTML5 Forms Polyfill). After reading this portion of the book, the reader should have everything she needs to know to build a traditional polyfill.
Next, the discussion will turn to an emerging trend on the web platform: the "experimental feature" polyfill. This pattern, seen in libraries like AngularJS and in W3C specifications like Web Components & Shadow DOM, enables developers to test and work with emerging concepts.
