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Add demo with a parent and child shadow tree #1

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Add demo with a parent and child shadow tree #1

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68cb70a
Add demo with a parent and child shadow tree
wkillerud Oct 2, 2025
b45a5f8
Set up example for referencing anchor in parent tree
wkillerud Oct 2, 2025
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5 changes: 5 additions & 0 deletions public/anchor-shadow-child.css
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
#child-target-positioning {
position: absolute;
right: anchor(--shadow-anchor-positioning right);
top: anchor(--shadow-anchor-positioning bottom);
}
3 changes: 3 additions & 0 deletions public/anchor-shadow-parent.css
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
#parent-anchor-positioning {
anchor-name: --shadow-anchor-positioning;
}
59 changes: 50 additions & 9 deletions shadow-root.html
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Original file line number Diff line number Diff line change
Expand Up @@ -37,13 +37,14 @@

if (!SUPPORTS_ANCHOR_POSITIONING) {
btn.addEventListener('click', () => {
document
.querySelector('anchor-web-component')
.applyPolyfill()
.then(() => {
btn.innerText = 'Polyfill Applied';
btn.setAttribute('disabled', '');
});
Promise.all(
[...document.querySelectorAll('[data-polyfillable]')].map((e) =>
e.applyPolyfill(),
),
).then(() => {
btn.innerText = 'Polyfill Applied';
btn.setAttribute('disabled', '');
});
});
} else {
btn.innerText = 'No Polyfill Needed';
Expand All @@ -53,13 +54,28 @@
);
}

class AnchorWebComponent extends HTMLElement {
class BaseWebComponent extends HTMLElement {
/* This would typically be run in connectedCallback() */
applyPolyfill() {
return polyfill({ root: [this.shadowRoot] });
}
}

class AnchorWebComponent extends BaseWebComponent {}
customElements.define('anchor-web-component', AnchorWebComponent);

class ParentComponent extends BaseWebComponent {}
customElements.define('parent-component', ParentComponent);

class ChildComponent extends BaseWebComponent {
connectedCallback() {
console.log({
shadowRoot: this.shadowRoot,
host: this.shadowRoot.host.parentNode.host.parentNode.parentNode,
});
}
}
customElements.define('child-component', ChildComponent);
</script>
<link rel="icon" href="/favicon.svg" type="image/svg+xml" />
<script src="https://unpkg.com/prismjs@v1.x/components/prism-core.min.js"></script>
Expand Down Expand Up @@ -182,7 +198,7 @@ <h2>
Works if anchor and target are both inside the same shadow root
</h2>
<div class="demo-elements">
<anchor-web-component>
<anchor-web-component data-polyfillable>
<template shadowrootmode="open">
<link rel="stylesheet" href="/demo.css" />
<link rel="stylesheet" href="/anchor-shadow-root.css" />
Expand Down Expand Up @@ -235,6 +251,31 @@ <h2>
&lt;/script&gt;
</code></pre>
</section>
<section id="nested-shadow-roots" class="demo-item">
<h2>
<a href="#nested-shadow-roots" aria-hidden="true">🔗</a>
Child shadow root can anchor to parent shadow root
</h2>
<div class="demo-elements">
<parent-component data-polyfillable>
<template shadowrootmode="open">
<link rel="stylesheet" href="/demo.css" />
<link rel="stylesheet" href="/anchor-shadow-parent.css" />
<div style="position: relative;">
<child-component data-polyfillable>
<template shadowrootmode="open">
<link rel="stylesheet" href="/demo.css" />
<link rel="stylesheet" href="/anchor-shadow-child.css" />
<div id="child-target-positioning" class="target">Target</div>
</template>
</child-component>

<div id="parent-anchor-positioning" class="anchor">Anchor</div>
</div>
</template>
</parent-component>
</div>
</section>
<section id="sponsor">
<h2>Sponsor OddBird’s OSS Work</h2>
<p>
Expand Down