fix: Properly check nodes before replacement (#457)

which is slightly different from the checks required when inserting a node. Also fixes the missing `Document.ownerDocument`, which prevented proper deletion of childNodes from `Document`. fixes #455 (only on the master branch for now, I want to test if this also takes care of #456) https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity https://dom.spec.whatwg.org/#concept-node-replace
xmldom · Nov 5, 2022 · b6ad6e9 · b6ad6e9
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,6 +4,15 @@ All notable changes to this project will be documented in this file.
 
 This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.8.6](https://github.com/xmldom/xmldom/compare/0.8.5...0.8.6)
+
+### Fixed
+
+- Properly check nodes before replacement [`#457`](https://github.com/xmldom/xmldom/pull/457) / [`#455`](https://github.com/xmldom/xmldom/issues/455) / [`#456`](https://github.com/xmldom/xmldom/issues/456)
+
+Thank you, [@edemaine](https://github.com/edemaine), [@pedro-l9](https://github.com/pedro-l9), for your contributions
+
+
 ## [0.8.5](https://github.com/xmldom/xmldom/compare/0.8.4...0.8.5)
 
 ### Fixed

diff --git a/lib/dom.js b/lib/dom.js
@@ -468,7 +468,7 @@ Node.prototype = {
 		return _insertBefore(this,newChild,refChild);
 	},
 	replaceChild:function(newChild, oldChild){//raises
-		this.insertBefore(newChild,oldChild);
+		_insertBefore(this, newChild,oldChild, assertPreReplacementValidityInDocument);
 		if(oldChild){
 			this.removeChild(oldChild);
 		}
@@ -590,6 +590,7 @@ function _visitNode(node,callback){
 
 
 function Document(){
+	this.ownerDocument = this;
 }
 
 function _onAddAttribute(doc,el,newAttr){
@@ -747,64 +748,200 @@ function isElementInsertionPossible(doc, child) {
 	var docTypeNode = find(parentChildNodes, isDocTypeNode);
 	return !(child && docTypeNode && parentChildNodes.indexOf(docTypeNode) > parentChildNodes.indexOf(child));
 }
+
 /**
+ * Check if en element node can be inserted before `child`, or at the end if child is falsy,
+ * according to the presence and position of a doctype node on the same level.
+ *
+ * @param {Node} doc The document node
+ * @param {Node} child the node that would become the nextSibling if the element would be inserted
+ * @returns {boolean} `true` if an element can be inserted before child
  * @private
+ * https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity
+ */
+function isElementReplacementPossible(doc, child) {
+	var parentChildNodes = doc.childNodes || [];
+
+	function hasElementChildThatIsNotChild(node) {
+		return isElementNode(node) && node !== child;
+	}
+
+	if (find(parentChildNodes, hasElementChildThatIsNotChild)) {
+		return false;
+	}
+	var docTypeNode = find(parentChildNodes, isDocTypeNode);
+	return !(child && docTypeNode && parentChildNodes.indexOf(docTypeNode) > parentChildNodes.indexOf(child));
+}
+
+/**
+ * @private
+ * Steps 1-5 of the checks before inserting and before replacing a child are the same.
+ *
  * @param {Node} parent the parent node to insert `node` into
  * @param {Node} node the node to insert
  * @param {Node=} child the node that should become the `nextSibling` of `node`
  * @returns {Node}
  * @throws DOMException for several node combinations that would create a DOM that is not well-formed.
  * @throws DOMException if `child` is provided but is not a child of `parent`.
  * @see https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity
+ * @see https://dom.spec.whatwg.org/#concept-node-replace
  */
-function _insertBefore(parent, node, child) {
+function assertPreInsertionValidity1to5(parent, node, child) {
+	// 1. If `parent` is not a Document, DocumentFragment, or Element node, then throw a "HierarchyRequestError" DOMException.
 	if (!hasValidParentNodeType(parent)) {
 		throw new DOMException(HIERARCHY_REQUEST_ERR, 'Unexpected parent node type ' + parent.nodeType);
 	}
+	// 2. If `node` is a host-including inclusive ancestor of `parent`, then throw a "HierarchyRequestError" DOMException.
+	// not implemented!
+	// 3. If `child` is non-null and its parent is not `parent`, then throw a "NotFoundError" DOMException.
 	if (child && child.parentNode !== parent) {
 		throw new DOMException(NOT_FOUND_ERR, 'child not in parent');
 	}
 	if (
+		// 4. If `node` is not a DocumentFragment, DocumentType, Element, or CharacterData node, then throw a "HierarchyRequestError" DOMException.
 		!hasInsertableNodeType(node) ||
+		// 5. If either `node` is a Text node and `parent` is a document,
 		// the sax parser currently adds top level text nodes, this will be fixed in 0.9.0
 		// || (node.nodeType === Node.TEXT_NODE && parent.nodeType === Node.DOCUMENT_NODE)
+		// or `node` is a doctype and `parent` is not a document, then throw a "HierarchyRequestError" DOMException.
 		(isDocTypeNode(node) && parent.nodeType !== Node.DOCUMENT_NODE)
 	) {
 		throw new DOMException(
 			HIERARCHY_REQUEST_ERR,
 			'Unexpected node type ' + node.nodeType + ' for parent node type ' + parent.nodeType
 		);
 	}
+}
+
+/**
+ * @private
+ * Step 6 of the checks before inserting and before replacing a child are different.
+ *
+ * @param {Document} parent the parent node to insert `node` into
+ * @param {Node} node the node to insert
+ * @param {Node | undefined} child the node that should become the `nextSibling` of `node`
+ * @returns {Node}
+ * @throws DOMException for several node combinations that would create a DOM that is not well-formed.
+ * @throws DOMException if `child` is provided but is not a child of `parent`.
+ * @see https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity
+ * @see https://dom.spec.whatwg.org/#concept-node-replace
+ */
+function assertPreInsertionValidityInDocument(parent, node, child) {
 	var parentChildNodes = parent.childNodes || [];
 	var nodeChildNodes = node.childNodes || [];
-	if (parent.nodeType === Node.DOCUMENT_NODE) {
-		if (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
-			var nodeChildElements = nodeChildNodes.filter(isElementNode);
-			if (nodeChildElements.length > 1 || find(nodeChildNodes, isTextNode)) {
-				throw new DOMException(HIERARCHY_REQUEST_ERR, 'More than one element or text in fragment');
-			}
-			if (nodeChildElements.length === 1 && !isElementInsertionPossible(parent, child)) {
-				throw new DOMException(HIERARCHY_REQUEST_ERR, 'Element in fragment can not be inserted before doctype');
-			}
+
+	// DocumentFragment
+	if (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
+		var nodeChildElements = nodeChildNodes.filter(isElementNode);
+		// If node has more than one element child or has a Text node child.
+		if (nodeChildElements.length > 1 || find(nodeChildNodes, isTextNode)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'More than one element or text in fragment');
 		}
-		if (isElementNode(node)) {
-			if (find(parentChildNodes, isElementNode) || !isElementInsertionPossible(parent, child)) {
-				throw new DOMException(HIERARCHY_REQUEST_ERR, 'Only one element can be added and only after doctype');
-			}
+		// Otherwise, if `node` has one element child and either `parent` has an element child,
+		// `child` is a doctype, or `child` is non-null and a doctype is following `child`.
+		if (nodeChildElements.length === 1 && !isElementInsertionPossible(parent, child)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Element in fragment can not be inserted before doctype');
 		}
-		if (isDocTypeNode(node)) {
-			if (find(parentChildNodes, isDocTypeNode)) {
-				throw new DOMException(HIERARCHY_REQUEST_ERR, 'Only one doctype is allowed');
-			}
-			var parentElementChild = find(parentChildNodes, isElementNode);
-			if (child && parentChildNodes.indexOf(parentElementChild) < parentChildNodes.indexOf(child)) {
-				throw new DOMException(HIERARCHY_REQUEST_ERR, 'Doctype can only be inserted before an element');
-			}
-			if (!child && parentElementChild) {
-				throw new DOMException(HIERARCHY_REQUEST_ERR, 'Doctype can not be appended since element is present');
-			}
+	}
+	// Element
+	if (isElementNode(node)) {
+		// `parent` has an element child, `child` is a doctype,
+		// or `child` is non-null and a doctype is following `child`.
+		if (!isElementInsertionPossible(parent, child)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Only one element can be added and only after doctype');
+		}
+	}
+	// DocumentType
+	if (isDocTypeNode(node)) {
+		// `parent` has a doctype child,
+		if (find(parentChildNodes, isDocTypeNode)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Only one doctype is allowed');
+		}
+		var parentElementChild = find(parentChildNodes, isElementNode);
+		// `child` is non-null and an element is preceding `child`,
+		if (child && parentChildNodes.indexOf(parentElementChild) < parentChildNodes.indexOf(child)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Doctype can only be inserted before an element');
+		}
+		// or `child` is null and `parent` has an element child.
+		if (!child && parentElementChild) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Doctype can not be appended since element is present');
 		}
 	}
+}
+
+/**
+ * @private
+ * Step 6 of the checks before inserting and before replacing a child are different.
+ *
+ * @param {Document} parent the parent node to insert `node` into
+ * @param {Node} node the node to insert
+ * @param {Node | undefined} child the node that should become the `nextSibling` of `node`
+ * @returns {Node}
+ * @throws DOMException for several node combinations that would create a DOM that is not well-formed.
+ * @throws DOMException if `child` is provided but is not a child of `parent`.
+ * @see https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity
+ * @see https://dom.spec.whatwg.org/#concept-node-replace
+ */
+function assertPreReplacementValidityInDocument(parent, node, child) {
+	var parentChildNodes = parent.childNodes || [];
+	var nodeChildNodes = node.childNodes || [];
+
+	// DocumentFragment
+	if (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
+		var nodeChildElements = nodeChildNodes.filter(isElementNode);
+		// If `node` has more than one element child or has a Text node child.
+		if (nodeChildElements.length > 1 || find(nodeChildNodes, isTextNode)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'More than one element or text in fragment');
+		}
+		// Otherwise, if `node` has one element child and either `parent` has an element child that is not `child` or a doctype is following `child`.
+		if (nodeChildElements.length === 1 && !isElementReplacementPossible(parent, child)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Element in fragment can not be inserted before doctype');
+		}
+	}
+	// Element
+	if (isElementNode(node)) {
+		// `parent` has an element child that is not `child` or a doctype is following `child`.
+		if (!isElementReplacementPossible(parent, child)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Only one element can be added and only after doctype');
+		}
+	}
+	// DocumentType
+	if (isDocTypeNode(node)) {
+		function hasDoctypeChildThatIsNotChild(node) {
+			return isDocTypeNode(node) && node !== child;
+		}
+
+		// `parent` has a doctype child that is not `child`,
+		if (find(parentChildNodes, hasDoctypeChildThatIsNotChild)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Only one doctype is allowed');
+		}
+		var parentElementChild = find(parentChildNodes, isElementNode);
+		// or an element is preceding `child`.
+		if (child && parentChildNodes.indexOf(parentElementChild) < parentChildNodes.indexOf(child)) {
+			throw new DOMException(HIERARCHY_REQUEST_ERR, 'Doctype can only be inserted before an element');
+		}
+	}
+}
+
+/**
+ * @private
+ * @param {Node} parent the parent node to insert `node` into
+ * @param {Node} node the node to insert
+ * @param {Node=} child the node that should become the `nextSibling` of `node`
+ * @returns {Node}
+ * @throws DOMException for several node combinations that would create a DOM that is not well-formed.
+ * @throws DOMException if `child` is provided but is not a child of `parent`.
+ * @see https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity
+ */
+function _insertBefore(parent, node, child, _inDocumentAssertion) {
+	// To ensure pre-insertion validity of a node into a parent before a child, run these steps:
+	assertPreInsertionValidity1to5(parent, node, child);
+
+	// If parent is a document, and any of the statements below, switched on the interface node implements,
+	// are true, then throw a "HierarchyRequestError" DOMException.
+	if (parent.nodeType === Node.DOCUMENT_NODE) {
+		(_inDocumentAssertion || assertPreInsertionValidityInDocument)(parent, node, child);
+	}
 
 	var cp = node.parentNode;
 	if(cp){
@@ -912,6 +1049,17 @@ Document.prototype = {
 		}
 		return _removeChild(this,oldChild);
 	},
+	replaceChild: function (newChild, oldChild) {
+		//raises
+		_insertBefore(this, newChild, oldChild, assertPreReplacementValidityInDocument);
+		newChild.ownerDocument = this;
+		if (oldChild) {
+			this.removeChild(oldChild);
+		}
+		if (isElementNode(newChild)) {
+			this.documentElement = newChild;
+		}
+	},
 	// Introduced in DOM Level 2:
 	importNode : function(importedNode,deep){
 		return importNode(this,importedNode,deep);

diff --git a/test/dom/document.test.js b/test/dom/document.test.js
@@ -163,4 +163,33 @@ describe('Document.prototype', () => {
 			expect(root.parentNode).toBeNull()
 		})
 	})
+	describe('replaceChild', () => {
+		it('should remove the only element and add the new one', () => {
+			const doc = new DOMImplementation().createDocument('', 'xml');
+			const initialFirstChild = doc.firstChild;
+			const replacement = doc.createElement('replaced');
+
+			doc.replaceChild(replacement, doc.firstChild);
+
+			expect(doc.childNodes).toHaveLength(1);
+			expect(initialFirstChild.parentNode).toBeNull();
+			expect(doc.documentElement.name).toBe(replacement.name);
+		});
+	});
+	describe('removeChild', () => {
+		it('should remove all connections to node', () => {
+			const doc = new DOMImplementation().createDocument('', 'xml');
+			doc.insertBefore(doc.createComment('just a comment'), doc.firstChild);
+			expect(doc.childNodes).toHaveLength(2);
+			const initialElement = doc.firstChild;
+
+			doc.removeChild(initialElement);
+
+			// expect(doc.documentElement).toBeNull();
+			expect(initialElement.parentNode).toBeNull();
+			expect(initialElement.nextSibling).toBeNull();
+			// expect(initialElement.previousSibling).toBeNull();
+			expect(doc.childNodes).toHaveLength(1);
+		});
+	});
 })