tuespetre / custom-elements

A polyfill for HTML Custom Elements v1

custom-elements

A polyfill for HTML Custom Elements

Building & Running Tests

1. Install web-component-tester

```bash
$ npm i -g web-component-tester
```

2. Checkout the webcomponentsjs v1 branch

```bash
$ git clone https://github.com/webcomponents/webcomponentsjs.git
$ cd webcomponentsjs
$ npm i
$ gulp build
```

3. Run tests

```bash
$ wct tests/CustomElements/v1/index.html -l chrome
```

4. Bower link to use in another project

```bash
$ bower link
$ cd {your project directory}
$ bower link webcomponentsjs
```

Differences from Spec

Most custom element reactions in the polyfill are driven from Mutation Observers and so are async in cases where the spec calls for synchronous reactions. There are some exceptions, like for Document.importNode() and Element.setAttribute.

To ensure that queued operations are complete, mostly useful for tests, you can enable flushing:

customElements.enableFlush = true;

// some DOM operations

customElements.flush();

// some more DOM operations dependent on reactions in the first set