Firefox 150 adds customElementRegistry property behind pref (#29371)

hamishwillee · web-flow · commit 18febefe94c4 · 2026-04-03T15:35:00.000+02:00
FF150 customElementRegistry on Document, Element, ShadowRoot behind pref
diff --git a/api/Document.json b/api/Document.json
@@ -2809,7 +2809,15 @@
             "chrome_android": "mirror",
             "edge": "mirror",
             "firefox": {
-              "version_added": false
+              "version_added": "150",
+              "flags": [
+                {
+                  "type": "preference",
+                  "name": "dom.scoped-custom-element-registries.enabled",
+                  "value_to_set": "true"
+                }
+              ],
+              "impl_url": "https://bugzil.la/2018900"
             },
             "firefox_android": "mirror",
             "oculus": "mirror",
diff --git a/api/Element.json b/api/Element.json
@@ -4454,7 +4454,15 @@
             "chrome_android": "mirror",
             "edge": "mirror",
             "firefox": {
-              "version_added": false
+              "version_added": "150",
+              "flags": [
+                {
+                  "type": "preference",
+                  "name": "dom.scoped-custom-element-registries.enabled",
+                  "value_to_set": "true"
+                }
+              ],
+              "impl_url": "https://bugzil.la/2018900"
             },
             "firefox_android": "mirror",
             "oculus": "mirror",
diff --git a/api/ShadowRoot.json b/api/ShadowRoot.json
@@ -152,7 +152,15 @@
             "chrome_android": "mirror",
             "edge": "mirror",
             "firefox": {
-              "version_added": false
+              "version_added": "150",
+              "flags": [
+                {
+                  "type": "preference",
+                  "name": "dom.scoped-custom-element-registries.enabled",
+                  "value_to_set": "true"
+                }
+              ],
+              "impl_url": "https://bugzil.la/2018900"
             },
             "firefox_android": "mirror",
             "oculus": "mirror",
