#637@patch: Fixes problem with HTMLSelectElement.selectedIndex not re…

packages/happy-dom/src/nodes/element/Element.ts

@@ -919,8 +919,17 @@ export default class Element extends Node implements IElement {
 	 * Removes an Attr node.
 	 *
 	 * @param attribute Attribute.
+	 * @returns Removed attribute.
 	 */
-	public removeAttributeNode(attribute: IAttr): void {
+	public removeAttributeNode(attribute: IAttr): IAttr {
+		const removedAttribute = this._attributes[attribute.name];
+
+		if (removedAttribute !== attribute) {
+			throw new DOMException(
+				`Failed to execute 'removeAttributeNode' on 'Element': The node provided is owned by another element.`
+			);
+		}
+
 		delete this._attributes[attribute.name];
 
 		if (this.isConnected) {
@@ -954,15 +963,18 @@ export default class Element extends Node implements IElement {
 				}
 			}
 		}
+
+		return attribute;
 	}
 
 	/**
 	 * Removes an Attr node.
 	 *
 	 * @param attribute Attribute.
+	 * @returns Removed attribute.
 	 */
-	public removeAttributeNodeNS(attribute: IAttr): void {
-		this.removeAttributeNode(attribute);
+	public removeAttributeNodeNS(attribute: IAttr): IAttr {
+		return this.removeAttributeNode(attribute);
 	}
 
 	/**

packages/happy-dom/src/nodes/element/IElement.ts

@@ -260,15 +260,17 @@ export default interface IElement extends IChildNode, INonDocumentTypeChildNode,
 	 * Removes an Attr node.
 	 *
 	 * @param attribute Attribute.
+	 * @returns Removed attribute.
 	 */
-	removeAttributeNode(attribute: IAttr): void;
+	removeAttributeNode(attribute: IAttr): IAttr;
 
 	/**
 	 * Removes an Attr node.
 	 *
 	 * @param attribute Attribute.
+	 * @returns Removed attribute.
 	 */
-	removeAttributeNodeNS(attribute: IAttr): void;
+	removeAttributeNodeNS(attribute: IAttr): IAttr;
 
 	/**
 	 * Clones a node.

packages/happy-dom/src/nodes/html-element/HTMLElement.ts

@@ -421,11 +421,7 @@ export default class HTMLElement extends Element implements IHTMLElement {
 	}
 
 	/**
-	 * The setAttributeNode() method adds a new Attr node to the specified element.
-	 *
 	 * @override
-	 * @param attribute Attribute.
-	 * @returns Replaced attribute.
 	 */
 	public setAttributeNode(attribute: IAttr): IAttr {
 		const replacedAttribute = super.setAttributeNode(attribute);
@@ -438,25 +434,20 @@ export default class HTMLElement extends Element implements IHTMLElement {
 	}
 
 	/**
-	 * Removes an Attr node.
-	 *
 	 * @override
-	 * @param attribute Attribute.
 	 */
-	public removeAttributeNode(attribute: IAttr): void {
+	public removeAttributeNode(attribute: IAttr): IAttr {
 		super.removeAttributeNode(attribute);
 
 		if (attribute.name === 'style' && this._style) {
 			this._style.cssText = '';
 		}
+
+		return attribute;
 	}
 
 	/**
-	 * Clones a node.
-	 *
 	 * @override
-	 * @param [deep=false] "true" to clone deep.
-	 * @returns Cloned node.
 	 */
 	public cloneNode(deep = false): IHTMLElement {
 		const clone = <HTMLElement>super.cloneNode(deep);

packages/happy-dom/src/nodes/html-option-element/HTMLOptionElement.ts

@@ -1,7 +1,8 @@
+import IAttr from '../attr/IAttr';
 import HTMLElement from '../html-element/HTMLElement';
 import IHTMLElement from '../html-element/IHTMLElement';
 import IHTMLFormElement from '../html-form-element/IHTMLFormElement';
-import IHTMLSelectElement from '../html-select-element/IHTMLSelectElement';
+import HTMLSelectElement from '../html-select-element/HTMLSelectElement';
 import IHTMLOptionElement from './IHTMLOptionElement';
 
 /**
@@ -12,6 +13,8 @@ import IHTMLOptionElement from './IHTMLOptionElement';
  */
 export default class HTMLOptionElement extends HTMLElement implements IHTMLOptionElement {
 	public _index: number;
+	public _selectedness = false;
+	public _dirtyness = false;
 
 	/**
 	 * Returns inner text, which is the rendered appearance of text.
@@ -59,20 +62,7 @@ export default class HTMLOptionElement extends HTMLElement implements IHTMLOptio
 	 * @returns Selected.
 	 */
 	public get selected(): boolean {
-		const parentNode = <IHTMLSelectElement>this.parentNode;
-
-		if (parentNode?.tagName === 'SELECT') {
-			let index = -1;
-			for (let i = 0; i < parentNode.options.length; i++) {
-				if (parentNode.options[i] === this) {
-					index = i;
-					break;
-				}
-			}
-			return index !== -1 && parentNode.options.selectedIndex === index;
-		}
-
-		return false;
+		return this._selectedness;
 	}
 
 	/**
@@ -81,26 +71,13 @@ export default class HTMLOptionElement extends HTMLElement implements IHTMLOptio
 	 * @param selected Selected.
 	 */
 	public set selected(selected: boolean) {
-		const parentNode = <IHTMLSelectElement>this.parentNode;
-		if (parentNode?.tagName === 'SELECT') {
-			if (selected) {
-				let index = -1;
-
-				for (let i = 0; i < parentNode.options.length; i++) {
-					if (parentNode.options[i] === this) {
-						index = i;
-						break;
-					}
-				}
-
-				if (index !== -1) {
-					parentNode.options.selectedIndex = index;
-				}
-			} else if (parentNode.options.length) {
-				parentNode.options.selectedIndex = 0;
-			} else {
-				parentNode.options.selectedIndex = -1;
-			}
+		const selectElement = this._getSelectElement();
+
+		this._dirtyness = true;
+		this._selectedness = Boolean(selected);
+
+		if (selectElement) {
+			selectElement._resetOptionSelectednes(this._selectedness ? this : null);
 		}
 	}
 
@@ -143,4 +120,61 @@ export default class HTMLOptionElement extends HTMLElement implements IHTMLOptio
 	public set value(value: string) {
 		this.setAttributeNS(null, 'value', value);
 	}
+
+	/**
+	 * @override
+	 */
+	public setAttributeNode(attribute: IAttr): IAttr {
+		const replacedAttribute = super.setAttributeNode(attribute);
+
+		if (
+			!this._dirtyness &&
+			attribute.name === 'selected' &&
+			replacedAttribute?.value !== attribute.value
+		) {
+			const selectElement = this._getSelectElement();
+
+			this._selectedness = true;
+
+			if (selectElement) {
+				selectElement._resetOptionSelectednes(this);
+			}
+		}
+
+		return replacedAttribute;
+	}
+
+	/**
+	 * @override
+	 */
+	public removeAttributeNode(attribute: IAttr): IAttr {
+		super.removeAttributeNode(attribute);
+
+		if (!this._dirtyness && attribute.name === 'selected') {
+			const selectElement = this._getSelectElement();
+
+			this._selectedness = false;
+
+			if (selectElement) {
+				selectElement._resetOptionSelectednes();
+			}
+		}
+
+		return attribute;
+	}
+
+	/**
+	 * Returns select element.
+	 *
+	 * @returns Select element.
+	 */
+	private _getSelectElement(): HTMLSelectElement {
+		const parentNode = <HTMLSelectElement>this.parentNode;
+		if (parentNode?.tagName === 'SELECT') {
+			return <HTMLSelectElement>parentNode;
+		}
+		if ((<HTMLSelectElement>parentNode?.parentNode)?.tagName === 'SELECT') {
+			return <HTMLSelectElement>parentNode.parentNode;
+		}
+	}
 }

packages/happy-dom/src/nodes/html-option-element/HTMLOptionsCollection.ts

@@ -16,7 +16,6 @@ export default class HTMLOptionsCollection
 	implements IHTMLOptionsCollection
 {
 	private _selectElement: IHTMLSelectElement;
-	private _selectedIndex = -1;
 
 	/**
 	 *
@@ -34,7 +33,7 @@ export default class HTMLOptionsCollection
 	 * @returns SelectedIndex.
 	 */
 	public get selectedIndex(): number {
-		return this._selectedIndex;
+		return this._selectElement.selectedIndex;
 	}
 
 	/**
@@ -43,13 +42,7 @@ export default class HTMLOptionsCollection
 	 * @param selectedIndex SelectedIndex.
 	 */
 	public set selectedIndex(selectedIndex: number) {
-		if (typeof selectedIndex === 'number' && !isNaN(selectedIndex)) {
-			if (selectedIndex >= 0 && selectedIndex < this.length) {
-				this._selectedIndex = selectedIndex;
-			} else {
-				this._selectedIndex = -1;
-			}
-		}
+		this._selectElement.selectedIndex = selectedIndex;
 	}
 
 	/**