feat(attributes): support button value on .val() (#4175)

src/__fixtures__/fixtures.ts

@@ -93,6 +93,8 @@ export const unwrapspans: string = [
 ].join('');
 
 export const inputs: string = [
+  '<button id="btn-value" value="button">Button</button>',
+  '<button id="btn-valueless">Button</button>',
   '<select id="one"><option value="option_not_selected">Option not selected</option><option value="option_selected" selected>Option selected</option></select>',
   '<select id="one-valueless"><option>Option not selected</option><option selected>Option selected</option></select>',
   '<select id="one-html-entity"><option>Option not selected</option><option selected>Option &lt;selected&gt;</option></select>',

src/api/attributes.spec.ts

@@ -652,6 +652,14 @@ describe('$(...)', () => {
       expect($('<div>').val()).toBeUndefined();
     });
 
+    it('(): on button should get value', () => {
+      const val = $('#btn-value').val();
+      expect(val).toBe('button');
+    });
+    it('(): on button with no value should get undefined', () => {
+      const val = $('#btn-valueless').val();
+      expect(val).toBeUndefined();
+    });
     it('(): on select should get value', () => {
       const val = $('select#one').val();
       expect(val).toBe('option_selected');
@@ -1025,7 +1033,7 @@ describe('$(...)', () => {
     it('(fn) : should no op elements without attributes', () => {
       const $inputs = $(inputs);
       const val = $inputs.removeClass(() => 'tasty');
-      expect(val).toHaveLength(15);
+      expect(val).toHaveLength(17);
     });
 
     it('(fn) : should skip text nodes', () => {

src/api/attributes.ts

@@ -811,6 +811,7 @@ export function val<T extends AnyNode>(
         ? option.toArray().map((el) => text(el.children))
         : option.attr('value');
     }
+    case 'button':
     case 'input':
     case 'option': {
       return querying