fix: [1706] Handle non string values gracefully for removeAttribute o…

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

@@ -33,6 +33,7 @@ import NodeFactory from '../NodeFactory.js';
 import HTMLSerializer from '../../html-serializer/HTMLSerializer.js';
 import HTMLParser from '../../html-parser/HTMLParser.js';
 import IScrollToOptions from '../../window/IScrollToOptions.js';
+import { AttributeUtility } from '../../utilities/AttributeUtility.js';
 
 type InsertAdjacentPosition = 'beforebegin' | 'afterbegin' | 'beforeend' | 'afterend';
 
@@ -669,6 +670,12 @@ export default class Element
 	 * @param value Value.
 	 */
 	public setAttribute(name: string, value: string): void {
+		AttributeUtility.validateAttributeName(
+			name,
+			this[PropertySymbol.ownerDocument][PropertySymbol.contentType],
+			{ method: 'setAttribute', instance: 'Element' }
+		);
+		name = String(name);
 		const namespaceURI = this[PropertySymbol.namespaceURI];
 		// TODO: Is it correct to check for namespaceURI === NamespaceURI.svg?
 		const attribute =

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

@@ -84,6 +84,7 @@ export default class NamedNodeMap {
 	 * @returns Item.
 	 */
 	public getNamedItem(name: string): Attr | null {
+		name = String(name);
 		if (
 			this[PropertySymbol.ownerElement][PropertySymbol.namespaceURI] === NamespaceURI.html &&
 			this[PropertySymbol.ownerElement][PropertySymbol.ownerDocument][

packages/happy-dom/src/utilities/AttributeUtility.ts

@@ -0,0 +1,43 @@
+import DOMException from '../exception/DOMException.js';
+import DOMExceptionNameEnum from '../exception/DOMExceptionNameEnum.js';
+
+const HTML_INVALID_ATTRIBUTE_NAME_CHARACTER_REGEX =
+	/[\x00-\x1F\x7F\x80-\x9F "\'><=\/\uFDD0-\uFDEF\uFFFE\uFFFF\u1FFFE\u1FFFF\u2FFFE\u2FFFF\u3FFFE\u3FFFF\u4FFFE\u4FFFF\u5FFFE\u5FFFF\u6FFFE\u6FFFF\u7FFFE\u7FFFF\u8FFFE\u8FFFF\u9FFFE\u9FFFF\uAFFFE\uAFFFF\uBFFFE\uBFFFF\uCFFFE\uCFFFF\uDFFFE\uDFFFF\uEFFFE\uEFFFF\uFFFFE\uFFFFF\u10FFFE\u10FFFF]/;
+
+/**
+ * Attribute utility
+ */
+export class AttributeUtility {
+	/**
+	 *
+	 * @param name the attribute name
+	 * @param contentType the attribute has to be valid in
+	 * @param context the context in which the error occurred in
+	 * @param context.method
+	 * @param context.instance
+	 */
+	public static validateAttributeName(
+		name: unknown,
+		contentType: string,
+		context: {
+			method: string;
+			instance: string;
+		}
+	): void {
+		const { method, instance } = context;
+		if (contentType === 'text/html') {
+			const normalizedName = String(name).toLowerCase();
+			if (
+				HTML_INVALID_ATTRIBUTE_NAME_CHARACTER_REGEX.test(normalizedName) ||
+				normalizedName.length === 0 ||
+				normalizedName[0] === '-'
+			) {
+				throw new DOMException(
+					`Uncaught InvalidCharacterError: Failed to execute '${method}' on '${instance}': '${name}' is not a valid attribute name.`,
+					DOMExceptionNameEnum.invalidCharacterError
+				);
+			}
+		}
+		// TODO: implement XML and other content types
+	}
+}

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

@@ -19,6 +19,7 @@ import NodeList from '../../../src/nodes/node/NodeList.js';
 import Event from '../../../src/event/Event.js';
 import { beforeEach, afterEach, describe, it, expect, vi } from 'vitest';
 import * as PropertySymbol from '../../../src/PropertySymbol.js';
+import DOMExceptionNameEnum from '../../../lib/exception/DOMExceptionNameEnum';
 
 const NAMESPACE_URI = 'https://test.test';
 
@@ -1566,6 +1567,162 @@ describe('Element', () => {
 			expect(element.attributes['key2'].ownerElement === element).toBe(true);
 			expect(element.attributes['key2'].ownerDocument === document).toBe(true);
 		});
+
+		it('Sets valid attribute names', () => {
+			// ✅ Basic letters (lowercase & uppercase)
+			element.setAttribute(`abc`, '1');
+			expect(element.getAttribute('abc')).toBe('1'); // lowercase letters
+
+			element.setAttribute(`ABC`, '1');
+			expect(element.getAttribute('ABC')).toBe('1'); // uppercase letters
+
+			element.setAttribute(`AbC`, '1');
+			expect(element.getAttribute('AbC')).toBe('1'); // mixed case
+
+			// ✅ Length variations
+			element.setAttribute(`a`, '1');
+			expect(element.getAttribute('a')).toBe('1'); // single character
+
+			element.setAttribute(`ab`, '1');
+			expect(element.getAttribute('ab')).toBe('1'); // two characters
+
+			element.setAttribute(`attribute`, '1');
+			expect(element.getAttribute('attribute')).toBe('1'); // common length
+
+			element.setAttribute(`averyverylongattributenamethatisvalid`, '1');
+			expect(element.getAttribute('averyverylongattributenamethatisvalid')).toBe('1'); // long attribute name
+
+			// ✅ Attribute names with digits
+			element.setAttribute(`attr1`, '1');
+			expect(element.getAttribute('attr1')).toBe('1'); // digit at the end
+
+			element.setAttribute(`a123`, '1');
+			expect(element.getAttribute('a123')).toBe('1'); // multiple digits at the end
+
+			element.setAttribute(`x9y`, '1');
+			expect(element.getAttribute('x9y')).toBe('1'); // digit in the middle
+
+			// ✅ Attribute names with allowed special characters
+			element.setAttribute(`_underscore`, '1');
+			expect(element.getAttribute('_underscore')).toBe('1'); // starts with underscore
+
+			element.setAttribute(`under_score`, '1');
+			expect(element.getAttribute('under_score')).toBe('1'); // contains underscore
+
+			element.setAttribute(`hyphen-ated`, '1');
+			expect(element.getAttribute('hyphen-ated')).toBe('1'); // contains hyphen
+
+			element.setAttribute(`ns:attribute`, '1');
+			expect(element.getAttribute('ns:attribute')).toBe('1'); // namespace-style (colon allowed)
+
+			// ✅ Unicode-based attribute names
+			element.setAttribute(`ö`, '1');
+			expect(element.getAttribute('ö')).toBe('1'); // Latin extended
+
+			element.setAttribute(`ñ`, '1');
+			expect(element.getAttribute('ñ')).toBe('1'); // Spanish tilde-n
+
+			element.setAttribute(`名`, '1');
+			expect(element.getAttribute('名')).toBe('1'); // Chinese character
+
+			element.setAttribute(`имя`, '1');
+			expect(element.getAttribute('имя')).toBe('1'); // Cyrillic (Russian)
+
+			element.setAttribute(`أسم`, '1');
+			expect(element.getAttribute('أسم')).toBe('1'); // Arabic script
+
+			element.setAttribute(`𝒜𝒷𝒸`, '1');
+			expect(element.getAttribute('𝒜𝒷𝒸')).toBe('1'); // Unicode math letters
+
+			element.setAttribute(`ⓐⓑⓒ`, '1');
+			expect(element.getAttribute('ⓐⓑⓒ')).toBe('1'); // Enclosed alphanumerics
+
+			element.setAttribute(`Ωμέγα`, '1');
+			expect(element.getAttribute('Ωμέγα')).toBe('1'); // Greek letters
+
+			// ✅ Edge cases
+			element.setAttribute(`a`, '1');
+			expect(element.getAttribute('a')).toBe('1'); // single lowercase letter
+
+			element.setAttribute(`Z`, '1');
+			expect(element.getAttribute('Z')).toBe('1'); // single uppercase letter
+
+			element.setAttribute(`_`, '1');
+			expect(element.getAttribute('_')).toBe('1'); // single underscore (valid but unusual)
+
+			// TODO: retest in XML content type
+			// element.setAttribute(`:`, '1');
+			// expect(element.getAttribute(':')).toBe('1'); // single colon (valid in XML namespaces)
+			// element.setAttribute(`-`, '1');
+			// expect(element.getAttribute('-')).toBe('1'); // single hyphen (valid in XML but discouraged in HTML)
+			// element.setAttribute(`-hyphen`, '1');
+			// expect(element.getAttribute('-hyphen')).toBe('1'); // starts with hyphen (allowed in XML)
+
+			element.setAttribute(`valid-attribute-name-123`, '1');
+			expect(element.getAttribute('valid-attribute-name-123')).toBe('1'); // mixed with hyphens and digits
+
+			element.setAttribute(`data-custom`, '1');
+			expect(element.getAttribute('data-custom')).toBe('1'); // common custom attribute pattern
+		});
+
+		it('Throws an error when given an invalid character in the attribute name', () => {
+			try {
+				element.setAttribute('☺', '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				// eslint-disable-next-line
+				element.setAttribute({} as string, '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute('', '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute('=', '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute(' ', '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute('"', '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute(`'`, '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute(`>`, '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute(`\/`, '1');
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute(`\u007F`, '1'); // control character delete
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+			try {
+				element.setAttribute(`\u9FFFE`, '1'); // non character
+			} catch (error) {
+				expect(error.name).toBe(DOMExceptionNameEnum.invalidCharacterError);
+			}
+		});
 	});
 
 	describe('setAttributeNS()', () => {
@@ -1646,6 +1803,12 @@ describe('Element', () => {
 			element.removeAttribute('key1');
 			expect(element.attributes.length).toBe(0);
 		});
+
+		it('Should stringify a non string attribute and remove it', () => {
+			element.setAttribute('undefined', 'value1');
+			element.removeAttribute(undefined);
+			expect(element.attributes.length).toBe(0);
+		});
 	});
 
 	describe('removeAttributeNS()', () => {

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

@@ -129,6 +129,11 @@ describe('NamedNodeMap', () => {
 			expect(element.getAttribute('key')).toBe('value1');
 			expect(element.getAttributeNS('namespace', 'key')).toBe('value2');
 		});
+
+		it('Handles non string keys as strings', () => {
+			element.setAttribute(undefined, 'value1');
+			expect(element.getAttribute('undefined')).toBe('value1');
+		});
 	});
 
 	describe('setNamedItemNS()', () => {