fix(attributes): Align prop undefined handling with jQuery

src/api/attributes.spec.ts

@@ -211,6 +211,13 @@ describe('$(...)', () => {
       expect(checkbox.prop('nodeName')).toBe('INPUT');
     });
 
+    it('(valid key) : should return on empty collection', () => {
+      expect($(undefined).prop('checked')).toBeUndefined();
+      expect($(undefined).prop('style')).toBeUndefined();
+      expect($(undefined).prop('tagName')).toBeUndefined();
+      expect($(undefined).prop('nodeName')).toBeUndefined();
+    });
+
     it('(invalid key) : invalid prop should get undefined', () => {
       expect(checkbox.prop('lol')).toBeUndefined();
       expect(checkbox.prop(4 as any)).toBeUndefined();
@@ -246,6 +253,12 @@ describe('$(...)', () => {
       expect(imgs.prop('data-foo')).toBeUndefined();
     });
 
+    it('(key, value) : should ignore empty collection', () => {
+      expect($(undefined).prop('checked')).toBeUndefined();
+      $(undefined).prop('checked', true);
+      expect($(undefined).prop('checked')).toBeUndefined();
+    });
+
     it('(map) : object map should set multiple props', () => {
       checkbox.prop({
         id: 'check',
@@ -300,6 +313,8 @@ describe('$(...)', () => {
       expect($('#2').prop('href')).toBe('http://example.org/');
       expect($('#3').prop('href')).toBe('http://example.com/example.org');
       expect($('#4').prop('href')).toBe('http://example.com/page/example.org');
+
+      expect($(undefined).prop('href')).toBeUndefined();
     });
 
     it('("src") : should resolve links with `baseURI`', () => {
@@ -321,19 +336,25 @@ describe('$(...)', () => {
       expect($('#4').prop('src')).toBe(
         'http://example.com/page/example.org/image.png'
       );
+
+      expect($(undefined).prop('src')).toBeUndefined();
     });
 
     it('("outerHTML") : should render properly', () => {
       const outerHtml = '<div><a></a></div>';
       const $a = $(outerHtml);
 
       expect($a.prop('outerHTML')).toBe(outerHtml);
+
+      expect($(undefined).prop('outerHTML')).toBeUndefined();
     });
 
     it('("innerHTML") : should render properly', () => {
       const $a = $('<div><a></a></div>');
 
       expect($a.prop('innerHTML')).toBe('<a></a>');
+
+      expect($(undefined).prop('innerHTML')).toBeUndefined();
     });
 
     it('("textContent") : should render properly', () => {
@@ -342,6 +363,8 @@ describe('$(...)', () => {
       );
 
       expect($(script).prop('textContent')).toBe('A  var foo = "bar";B');
+
+      expect($(undefined).prop('textContent')).toBeUndefined();
     });
 
     it('("textContent") : should include style and script tags', () => {
@@ -363,6 +386,8 @@ describe('$(...)', () => {
       );
 
       expect($(script).prop('innerText')).toBe('AB');
+
+      expect($(undefined).prop('innerText')).toBeUndefined();
     });
 
     it('("innerText") : should omit style and script tags', () => {

src/api/attributes.ts

@@ -235,12 +235,10 @@ export function attr<T extends AnyNode>(
  * @returns The prop's value.
  */
 function getProp(
-  el: AnyNode | undefined,
+  el: Element,
   name: string,
   xmlMode?: boolean
 ): string | undefined | Element[keyof Element] {
-  if (!el || !isTag(el)) return;
-
   return name in el
     ? // @ts-expect-error TS doesn't like us accessing the value directly here.
       el[name]
@@ -308,15 +306,15 @@ export function prop<T extends AnyNode>(
 export function prop<T extends AnyNode>(
   this: Cheerio<T>,
   name: 'style'
-): StyleProp;
+): StyleProp | undefined;
 /**
  * Resolve `href` or `src` of supported elements. Requires the `baseURI` option
  * to be set, and a global `URL` object to be part of the environment.
  *
  * @example With `baseURI` set to `'https://example.com'`:
  *
  * ```js
- * $('<img src="image.png">).prop('src');
+ * $('<img src="image.png">').prop('src');
  * //=> 'https://example.com/image.png'
  * ```
  */
@@ -363,6 +361,10 @@ export function prop<T extends AnyNode>(
     | unknown
 ): Cheerio<T> | string | undefined | null | Element[keyof Element] | StyleProp {
   if (typeof name === 'string' && value === undefined) {
+    const el = this[0];
+
+    if (!el || !isTag(el)) return undefined;
+
     switch (name) {
       case 'style': {
         const property = this.css() as StyleProp;
@@ -377,18 +379,11 @@ export function prop<T extends AnyNode>(
       }
       case 'tagName':
       case 'nodeName': {
-        const el = this[0];
-        return isTag(el) ? el.name.toUpperCase() : undefined;
+        return el.name.toUpperCase();
       }
 
       case 'href':
       case 'src': {
-        const el = this[0];
-
-        if (!isTag(el)) {
-          return undefined;
-        }
-
         const prop = el.attribs?.[name];
 
         /* eslint-disable node/no-unsupported-features/node-builtins */
@@ -411,11 +406,13 @@ export function prop<T extends AnyNode>(
         return prop;
       }
 
-      case 'innerText':
-        return innerText(this[0]);
+      case 'innerText': {
+        return innerText(el);
+      }
 
-      case 'textContent':
-        return textContent(this[0]);
+      case 'textContent': {
+        return textContent(el);
+      }
 
       case 'outerHTML':
         return this.clone().wrap('<container />').parent().html();
@@ -424,7 +421,7 @@ export function prop<T extends AnyNode>(
         return this.html();
 
       default:
-        return getProp(this[0], name, this.options.xmlMode);
+        return getProp(el, name, this.options.xmlMode);
     }
   }