Merge pull request #752 from btea/task/724-add-toggleAttribute

#724@minor: Add toggleAttribute.

Author: capricorn86

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

@@ -591,6 +591,30 @@ export default class Element extends Node implements IElement {
 		return null;
 	}
 
+	/**
+	 * Toggle an attribute.
+	 * Returns `true` if attribute name is eventually present, and `false` otherwise.
+	 *
+	 * @param name A DOMString specifying the name of the attribute to be toggled.
+	 * @param force A boolean value to determine whether the attribute should be added or removed, no matter whether the attribute is present or not at the moment.
+	 */
+	public toggleAttribute(name: string, force?: boolean): boolean {
+		name = name.toLowerCase();
+		const attribute = this.getAttributeNode(name);
+		if (attribute) {
+			if (force === true) {
+				return true;
+			}
+			this.removeAttributeNode(attribute);
+			return false;
+		}
+		if (force === false) {
+			return false;
+		}
+		this.setAttribute(name, '');
+		return true;
+	}
+
 	/**
 	 * Returns namespace attribute value.
 	 *

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

@@ -168,6 +168,14 @@ export default interface IElement extends IChildNode, INonDocumentTypeChildNode,
 	 */
 	removeAttributeNS(namespace: string, localName: string): void;
 
+	/**
+	 * Toggle an attribute.
+	 *
+	 * @param name A DOMString specifying the name of the attribute to be toggled.
+	 * @param force A boolean value to determine whether the attribute should be added or removed, no matter whether the attribute is present or not at the moment.
+	 */
+	toggleAttribute(name: string, force?: boolean): boolean;
+
 	/**
 	 * Attaches a shadow root.
 	 *

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

@@ -1232,6 +1232,21 @@ describe('Element', () => {
 		});
 	});
 
+	describe('toggleAttribute()', () => {
+		it('Toggles an attribute.', () => {
+			element.toggleAttribute('key1');
+			expect(element.hasAttribute('key1')).toBe(true);
+			element.toggleAttribute('key1');
+			expect(element.hasAttribute('key1')).toBe(false);
+			element.toggleAttribute('key1', true);
+			expect(element.hasAttribute('key1')).toBe(true);
+			element.toggleAttribute('key1', true);
+			expect(element.hasAttribute('key1')).toBe(true);
+			element.toggleAttribute('key1', false);
+			expect(element.hasAttribute('key1')).toBe(false);
+		});
+	});
+
 	describe('attachShadow()', () => {
 		it('Creates a new open ShadowRoot node and sets it to the "shadowRoot" property.', () => {
 			element.attachShadow({ mode: 'open' });