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Comprehensive set of high-quality web components for common user interface patterns
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NOTE (2017 May 24): This project has been subsumed by the Elix web components library. Elix has the same core principles, but has an expanded, more open governance model which we hope will help Elix find broad adoption. Elix uses the same mixin architecture as Basic Web Components, and many of the components and mixins from Basic Web Components are being migrated to Elix. We have stopped active development on Basic Web Components so that we can concentrate on Elix. Thank you for your support and interest in Basic Web Components, and apologies for any inconvenience caused by this change.


The Basic Web Components project seeks to provide a comprehensive set of solid, well-designed web components that implement very common user interface patterns. Each component can be used as is, or as the foundation for new components.

The master branch of this project targets Shadow DOM version 1 and Custom Elements version 1. Currently, the only browser that supports those specifications well enough is Google Chrome. That is currently the only browser in which all unit tests pass and all components work properly. We will be adding support for Safari Technology Preview and the version 1 polyfills as those stabilize.

In the meantime, for production use, you can continue to use the latest stable release, Basic Web Components 0.8.0, with the Shadow DOM and Custom Elements version 0 polyfills.


Design goals for the overall project:

  • Usability excellence. All components are designed, first and foremost, with the end user in mind. Each component tries to provide the best implementation possible of a very common user interface pattern. Using these in your application should improve the overall usability of your application.
  • Work in a wide variety of situations. By their nature, general-purpose components should work predictably and reliably in a wide variety of contexts. In that regard, these components are measured against Gold Standard for web components. That standard uses the built-in HTML elements as the quality bar to which these components aspire.
  • Completeness. In order to meet the above standard of quality, these components try to support a complete range of input modalities (touch, mouse, keyboard, trackpad, etc.) and responsive output. If the underlying user interface pattern has accessibility implications, the component tries to address those to the maximum extent possible. Because applications often have specific needs, however, the components are also designed to be extensible, as addressed by the next point.
  • Provide good building blocks. The project's components are designed to be used as-is, without requiring customization or further coding. But since no design can meet every situation, you can readily recombine their constituent parts to create solid custom components of your own. Composition is generally preferred over class inheritance as a means of aggregating behavior; see the basic-component-mixins package for details.
  • Leverage the browser platform as much as possible. These components are generally written as "close to the metal" as is possible while allowing for sharing code across components. These components are not built upon a monolithic framework, nor is any shared runtime required to use these components. At the same time, by virtue of being web components, these user interface elements can interoperate with any front-end framework.
  • Write in plain JavaScript ES6. An ES5 version of each component is provided in its /dist folder, so you can use these in ES5 projects. If you are already using ES6, you can use the ES6 source directly.
  • Provide a minimalist appearance. These components are meant to fit unobtrusively into your application, not present heavily styled or branded appearances of their own.
  • Work on all mainstream browsers. This includes the latest versions of Apple Safari and Mobile Safari, Google Chrome and Chrome for Android, Microsoft Edge and Internet Explorer (version 11), and Mozilla Firefox.

Repository organization

All work on Basic Web Components happens in this monorepo, keeping all sources in a single place. This makes it easy to clone, develop in, and track issues and pull requests.

The /packages folder contains the components and other cohesive units are registered with npm as separately installable packages. E.g., the source for the basic-autosize-textarea component is found in /packages/basic-autosize-textarea.

Installing components via npm

You can install the specific components you want via npm. To add a component like basic-autosize-textarea, add a line to the dependencies key in your project's package.json file. Until native Shadow DOM support is available on all browsers you want to support, you'll want to include the webcomponents.js polyfill as well:

  "dependencies": {
    "basic-autosize-textarea": "^0.7",
    "webcomponents.js": "^0.7.2"

Then issue an npm install as usual.

Once the component's package is installed, you can use the component in HTML and JavaScript. In HTML, you can load the script defining the component from the package's /dist folder:

  <script src="node_modules/webcomponents.js/webcomponents.js"></script>
  <script src="node_modules/basic-autosize-textarea/dist/basic-autosize-textarea.js"></script>
  <basic-autosize-textarea>Type all you want here!</basic-autosize-textarea>

If you're working in ES6, you can load a component with an import statement that references the component's ES6 .js file in the package's /src folder:

import AutosizeTextarea from 'basic-autosize-textarea/src/basic-autosize-textarea';

For more information on each component's purpose and API, see the component's README file at the top level of its package folder.

A sample-component project demonstrates the use of npm to depend on a Basic Web Components package.

Early versions of this library were distributed via the Bower package manager, but those packages were deprecated in the transition to using npm.

Using this repository to run demos

  1. Clone this repository to your local machine.
  2. Find the component you are interested in the /packages folder.
  3. Open the index.html page for that component to view its demo.

Project contents

The current release of Basic Web Components includes the following:

Top-level components

  • basic-animation-stage. A panel that shows animated transitions between selection states.
  • basic-autosize-textarea. A text area that expands to contain its text.
  • basic-carousel. Lets the user navigate laterally through a sequence of child elements.
  • basic-collapsible-panel. A panel which can be expanded/collapsed with an animated transition.
  • basic-current-anchor. An anchor (link) that highlights itself when its destination matches the current location.
  • basic-list-box. A single-selection list box that supports selection highlighting (using the system highlight color) and keyboard navigation.
  • basic-modes. Shows one child element at a time.
  • basic-sliding-carousel. A simpler version of basic-carousel (above) with lower requirements.
  • basic-slideshow. Slideshow with animated transitions.
  • basic-tabs. A set of pages with a tab strip governing which page is shown.

Helper components

These aren't usually instantiated on their own, but are used in conjunction with other components.


Mixins are a core part of the Basic Web Components approach to creating functionally sophisticated components. The basic-component-mixins library includes a variety of mixins you can use in your own components.

Desired components

Our vision is to eventually provide a solid implementation of all common user interface patterns in web applications. If you're interested in creating a web component that others can use, why not take a shot at one of the general-purpose components in our list of Desired Components and help us complete the collection?


The Basic Web Components project is open source under the MIT license. The project is led by Component Kitchen and sponsored in part by Google. The Basic Web Components project encourages you to join in and contribute general-purpose components to this effort! We'd love the help.


Thanks to use of the web component standards, these web components interoperate cleanly with other web components. For example, these Basic Web Components may used in combination with components created by frameworks such as Polymer, and Polymer features such as a data binding can be used on Basic Web Components. For a simple example, see carousel-with-tabs.

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