Web Components

A cross-platform extension mechanism allows anyone to add new elements to the html they write. Wilson Page reflects on the four years of decision making for this emerging standard. mozilla


Of all the Web Components technologies, Custom Elements have been the least contentious. There is general agreement on the value of being able to define how a piece of UI looks and behaves and being able to distribute that piece cross-browser and cross-framework.

Web Components are a prime example of how difficult it is to get large features into the browser today. Every API added lives indefinitely and remains as an obstacle to the next.

Comparable to picking apart a huge knotted ball of string, adding a bit more, then tangling it back up again. This knot, our platform, grows ever larger and more complex.


The browser's native tag dispatching can be extended with javascript. This will allow content authors familiar access to site based user-interface abstractions. Many frameworks provide this illusion already. Uniformity and cross-framework interoperability are the benefits of standards-based native browser implementation.

This status report summarizes the nature of issues for which browser vendors will come to agreement with an important meeting impending.

Browsers agree on how extensions will load.

Browsers agree how existing tags can be extended.

Browsers agree how dom elements carry new properties.

Browsers agree about visibility between extensions.

Browsers agree about scope of styling of extensions.

Browsers agree how extensions inherit from each other.

Browsers agree if html import serves as extension.

Federated wiki extends its own markup with uniformly configured plugins identified with a type field in each story item. See Abstraction of Method