Add experimental features for Fx 122: shadowrootmode, async clipboard

files/en-us/mozilla/firefox/experimental_features/index.md

@@ -99,6 +99,46 @@ HTML password input elements ([`<input type="password">`](/en-US/docs/Web/HTML/E
   </tbody>
 </table>
 
+### Declarative shadow DOM
+
+The {{htmlelement("template")}} element now supports a `shadowrootmode` attribute which can be set to either `open` or `closed`, the same values as the `mode` option of {{domxref("Element.attachShadow()", "attachShadow()")}} method. It allows the creation of a shadow DOM subtree declaratively. (See [Firefox bug 1712140](https://bugzil.la/1712140) for more details.)
+
+<table>
+  <thead>
+    <tr>
+      <th>Release channel</th>
+      <th>Version added</th>
+      <th>Enabled by default?</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <th>Nightly</th>
+      <td>122</td>
+      <td>Yes</td>
+    </tr>
+    <tr>
+      <th>Developer Edition</th>
+      <td>122</td>
+      <td>No</td>
+    </tr>
+    <tr>
+      <th>Beta</th>
+      <td>122</td>
+      <td>No</td>
+    </tr>
+    <tr>
+      <th>Release</th>
+      <td>122</td>
+      <td>No</td>
+    </tr>
+    <tr>
+      <th>Preference name</th>
+      <td colspan="2"><code>dom.webcomponents.shadowdom.declarative.enabled</code></td>
+    </tr>
+  </tbody>
+</table>
+
 ## CSS
 
 ### Hex boxes to display stray control characters

files/en-us/mozilla/firefox/releases/122/index.md

@@ -78,6 +78,18 @@ This article provides information about the changes in Firefox 122 that affect d
 
 These features are newly shipped in Firefox 122 but are disabled by default. To experiment with them, search for the appropriate preference on the `about:config` page and set it to `true`. You can find more such features on the [Experimental features](/en-US/docs/Mozilla/Firefox/Experimental_features) page.
 
+- Declarative shadow DOM: `dom.webcomponents.shadowdom.declarative.enabled`
+
+  The {{htmlelement("template")}} element now supports a `shadowrootmode` attribute which can be set to either `open` or `closed`, the same values as the `mode` option of {{domxref("Element.attachShadow()", "attachShadow()")}} method. It allows the creation of a shadow DOM subtree declaratively. ([Firefox bug 1712140](https://bugzil.la/1712140))
+
+- Popover API: `dom.element.popover.enabled`
+
+  Displaying popovers on top of page content is now supported via HTML attributes or JavaScript API, including styling with the CSS [`:popover-open`](/en-US/docs/Web/CSS/:popover-open) pseudo-class and extended support for the [`::backdrop`](/en-US/docs/Web/CSS/::backdrop) pseudo-element. See the [Popover API](/en-US/docs/Web/API/Popover_API) reference for more details. ([Firefox bug 1823757](https://bugzil.la/1823757))
+
+- Clipboard read and write: `dom.events.asyncClipboard.clipboardItem`, `dom.events.asyncClipboard.readText` and `dom.events.asyncClipboard.writeText`
+
+  The async {{domxref('Clipboard API')}} is now fully supported, including [`read()`](/en-US/docs/Web/API/Clipboard/read), [`readText()`](/en-US/docs/Web/API/Clipboard/readText), and [`write()`](/en-US/docs/Web/API/Clipboard/write) methods and the {{domxref('ClipboardItem')}} interface. A paste context menu will appear for the user to confirm when reading clipboard data not provided by the same-origin page. ([Firefox bug 1809106](https://bugzil.la/1809106))
+
 ## Older versions
 
 {{Firefox_for_developers(121)}}