capricorn86#1176@patch: Implement customElements.getName().

packages/happy-dom/src/custom-element/CustomElementRegistry.ts

@@ -89,4 +89,17 @@ export default class CustomElementRegistry {
 			this._callbacks[upperTagName].push(resolve);
 		});
 	}
+
+	/**
+	 * Reverse lookup searching for tagName by given element class.
+	 *
+	 * @param elementClass Class constructor.
+	 * @returns First found Tag name or `null`.
+	 */
+	public getName(elementClass: typeof HTMLElement): string | null {
+		const tagName = Object.keys(this._registry).find(
+			(k) => this._registry[k].elementClass === elementClass
+		);
+		return !!tagName ? tagName : null;
+	}
 }

packages/happy-dom/test/custom-element/CustomElementRegistry.test.ts

@@ -68,4 +68,15 @@ describe('CustomElementRegistry', () => {
 			});
 		});
 	});
+
+	describe('getName()', () => {
+		it('Returns null if no tagName is found in the registry for element class', () => {
+			expect(customElements.getName(CustomElement)).toBe(null);
+		});
+
+		it('Returns Tag name if element class is found in registry', () => {
+			customElements.define('custom-element', CustomElement);
+			expect(customElements.getName(CustomElement)).toMatch(/custom-element/i);
+		});
+	});
 });