The Heart of X-Tag
JavaScript CSS HTML
Latest commit b04c46a Feb 3, 2017 @csuwildcat csuwildcat committed on GitHub Merge pull request #168 from x-tag/mixin-fix-1
Ensure object exists before accessing .mixin

X-Tag - Rocket fuel for component development

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Bower version

NPM version


This is the repository for the core X-Tag library.

X-Tag is a Microsoft supported, open source, JavaScript library that wraps the W3C standard Web Components family of APIs to provide a compact, feature-rich interface for rapid component development. While X-Tag offers feature hooks for all Web Component APIs (Custom Elements, Shadow DOM, Templates, and HTML Imports), it only requires Custom Element support to operate. In the absence of native Custom Element support, X-Tag uses a set of polyfills shared with Google's Polymer framework.

You can find out more about what X-Tag does, where it works, and how to use it, on the project page:

Snag X-Tag from NPM

npm install x-tag

Pull our repo from Github

To get started hacking on X-Tag core:

git clone x-tag-core --recursive
cd x-tag-core
npm install        # installs all the required dependencies using package.json
grunt build     # outputs x-tag-core.js and x-tag-core.min.js to ./dist

If you are interested in building your own custom elements, you can use our web-component-stub as a starting point.


If you already cloned the library and want to update your build with changes to Core, do:

cd x-tag-core
git pull origin master
npm install
grunt build

This assumes you just cloned the library and its remote repository is labelled origin. Suppose you had your own fork where your own remote is origin; you should add another remote origin and label it as upstream. Then your git pull line would need to be git pull upstream master instead.


We use Jasmine to test the library, and you can verify it works as expected by opening test/index.html in your browser to run the tests.

Regenerating the distributable build

In the interest of not reinventing the wheel, X-Tag core uses a few existing libraries which get pulled into the project. But distributing a bunch of separate files is not efficient, so we need to generate a single file that contains all this code.

If you make changes on the library and want to regenerate the build, just run

grunt build

and both x-tag-core.js and x-tag-core.min.js will be rebuilt and placed in the ./dist directory.

Creating your own web components

To learn more about X-Tags visit

To create your own component, use our web-component-stub.

Share your components by adding them to the Custom Elements Registry or Bower.