@webcomponents/shadydom
v1.11.0
Published
Shadow DOM polyfill
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ShadyDOM
ShadyDOM provides a shim for ShadowDOM V1. It is less correct but less intrusive and faster than the ShadowDOM Polyfill.
Usage
Usage of the shim is transparent when attachShadow
is unavailable. Elements are
patched as needed to report ShadowDOM correct dom information. Only dom tree
accessors and mutation api is maintained. Some dom api
(for example MutationObservers) is not shimmed.
To force ShadyDOM to be used even when native ShadowDOM is available, set
the ShadyDOM = {force: true}
in a script prior to loading the polyfill.
Example
<div id="host"></div>
<script>
host.attachShadow({mode: 'open'});
host.shadowRoot.appendChild(document.createElement('a'));
</script>
Building and Testing
For building and testing, first run
npm install
npm run build
To test, run npm test
Limitations
ShadyDOM distribution is asynchronous for performance reasons. This means that
the composed dom will be available 1 microtask after the dom mutation occurs.
For testing, ShadyDOM.flush
may be called to force syncronous composition.
ShadowDOM compatible styling is not provided with the ShadyDOM shim. To shim ShadowDOM styling, use the shadycss shim.
On very old versions of Chrome and Safari, in rare cases ShadyDOM.patch(node)
must be called to properly set textContent
or innerHTML
. On these browsers,
element property accessors like firstChild
and textContent
cannot be
modified on the element prototype and instances must be patched. This is
automated but there are some cases that are not handled.
This should only be an issue when setting textContent
or innerHTML
on a
node inside a shadowRoot adds or removes a <slot>
element.
In this case, the shadowRoot will not render correctly. To workaround this,
call ShadyDOM.patch(node)
prior to setting textContent
or innerHTML
.
The APIs Document.querySelectorAll
, Element.querySelectorAll
, Node.childNodes
,
and ParentNode.children
each return an Array
instead of a NodeList
or HTMLCollection
.