3 files changed, 37 insertions, 0 deletions
diff --git a/dom/base/nsINode.cpp b/dom/base/nsINode.cpp
index 735dfb16e5..d4129171cb 100644
--- a/dom/base/nsINode.cpp
+++ b/dom/base/nsINode.cpp
@@ -1963,6 +1963,40 @@ nsINode::Append(const Sequence<OwningNodeOrString>& aNodes,
   AppendChild(*node, aRv);
 }
 
+// https://dom.spec.whatwg.org/#dom-parentnode-replacechildren
+void nsINode::ReplaceChildren(const Sequence<OwningNodeOrString>& aNodes,
+                              ErrorResult& aRv) {
+  nsCOMPtr<nsIDocument> doc = OwnerDoc();
+  nsCOMPtr<nsINode> node = ConvertNodesOrStringsIntoNode(aNodes, doc, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  EnsurePreInsertionValidity(*node, nullptr, aRv);
+  if (aRv.Failed()) {
+    return;
+  }
+
+  // Needed when used in combination with contenteditable (maybe)
+  mozAutoDocUpdate updateBatch(doc, UPDATE_CONTENT_MODEL, true);
+
+  nsAutoMutationBatch mb(this, true, false);
+
+  // Replace all with node within this.
+  while (mFirstChild) {
+    int32_t index = IndexOf(mFirstChild);
+    if (index == -1) {
+      NS_ASSERTION(index != -1, "First child must have an index");
+      return;
+    }
+    RemoveChildAt(index, true);
+  }
+  mb.RemovalDone();
+
+  AppendChild(*node, aRv);
+  mb.NodesAdded();
+}
+
 void
 nsINode::doRemoveChildAt(uint32_t aIndex, bool aNotify,
                          nsIContent* aKid, nsAttrAndChildArray& aChildArray)
diff --git a/dom/base/nsINode.h b/dom/base/nsINode.h
index 3611a4074d..5268767a3e 100644
--- a/dom/base/nsINode.h
+++ b/dom/base/nsINode.h
@@ -1980,6 +1980,7 @@ public:
 
   void Prepend(const Sequence<OwningNodeOrString>& aNodes, ErrorResult& aRv);
   void Append(const Sequence<OwningNodeOrString>& aNodes, ErrorResult& aRv);
+  void ReplaceChildren(const Sequence<OwningNodeOrString>& aNodes, ErrorResult& aRv);
 
   void GetBoxQuads(const BoxQuadOptions& aOptions,
                    nsTArray<RefPtr<DOMQuad> >& aResult,
diff --git a/dom/webidl/ParentNode.webidl b/dom/webidl/ParentNode.webidl
index aa6ca5db2c..6aa555744e 100644
--- a/dom/webidl/ParentNode.webidl
+++ b/dom/webidl/ParentNode.webidl
@@ -22,4 +22,6 @@ interface ParentNode {
   void prepend((Node or DOMString)... nodes);
   [CEReactions, Throws, Unscopable]
   void append((Node or DOMString)... nodes);
+  [CEReactions, Throws, Unscopable]
+  void replaceChildren((Node or DOMString)... nodes);
 };