Introducing Shadow DOM API in WebKit

We’re pleased to announce that basic support for the new slot-based shadow DOM API we proposed in April is now available in the nightly builds of WebKit after r190680. Shadow DOM is a part of Web Components, a set of specifications that were initially proposed by Google to enable the creation of reusable widgets and components on the Web. Shadow DOM, in particular, provides a lightweight encapsulation for DOM trees by allowing a creation of a parallel tree on an element called a “shadow tree” that replaces the rendering of the element without modifying the underlying DOM tree. Because a shadow tree is not an ordinary child of the “host” element to which it is attached, users of components cannot accidentally poke into it. Style rules are also scoped, meaning that CSS rules defined outside of a shadow tree do not apply to elements inside the shadow tree and rules defined inside the shadow tree do not apply to elements outside of it.