fix: [#1218] Adds missing setter for the HTMLImageElement.loading pro…

…perty

packages/happy-dom/src/nodes/html-image-element/HTMLImageElement.ts

@@ -50,7 +50,17 @@ export default class HTMLImageElement extends HTMLElement implements IHTMLImageE
 	 * @returns Loading.
 	 */
 	public get loading(): string {
-		return this[PropertySymbol.loading];
+		const loading = this.getAttribute('loading');
+		return loading === 'eager' || loading === 'lazy' ? loading : 'auto';
+	}
+
+	/**
+	 * Sets loading.
+	 *
+	 * @param loading Loading.
+	 */
+	public set loading(loading: string) {
+		this.setAttribute('loading', loading);
 	}
 
 	/**

packages/happy-dom/test/nodes/html-image-element/HTMLImageElement.test.ts

@@ -109,10 +109,36 @@ describe('HTMLImageElement', () => {
 	});
 
 	describe('get loading()', () => {
-		it('Returns "auto".', () => {
+		it('Returns "auto" by default.', () => {
 			const element = <HTMLImageElement>document.createElement('img');
 			expect(element.loading).toBe('auto');
 		});
+
+		it('Returns "eager" if the attribute is set to "eager".', () => {
+			const element = <HTMLImageElement>document.createElement('img');
+			element.setAttribute('loading', 'eager');
+			expect(element.loading).toBe('eager');
+		});
+
+		it('Returns "lazy" if the attribute is set to "lazy".', () => {
+			const element = <HTMLImageElement>document.createElement('img');
+			element.setAttribute('loading', 'lazy');
+			expect(element.loading).toBe('lazy');
+		});
+
+		it('Returns "auto" if value is invalid.', () => {
+			const element = <HTMLImageElement>document.createElement('img');
+			element.setAttribute('loading', 'invalid');
+			expect(element.loading).toBe('auto');
+		});
+	});
+
+	describe('set loading()', () => {
+		it('Sets the "loading" attribute.', () => {
+			const element = <HTMLImageElement>document.createElement('img');
+			element.loading = 'anyValueIsAllowed';
+			expect(element.getAttribute('loading')).toBe('anyValueIsAllowed');
+		});
 	});
 
 	describe('get x()', () => {