fix(datetime): confirm method now uses selected date (#24827)

Resolves #24823

core/src/components/datetime/datetime.tsx

@@ -424,10 +424,10 @@ export class Datetime implements ComponentInterface {
      * the date that is currently selected, otherwise
      * there can be 1 hr difference when dealing w/ DST
      */
-    const date = new Date(convertDataToISO(this.workingParts));
-    this.workingParts.tzOffset = date.getTimezoneOffset() * -1;
+    const date = new Date(convertDataToISO(this.activeParts));
+    this.activeParts.tzOffset = date.getTimezoneOffset() * -1;
 
-    this.value = convertDataToISO(this.workingParts);
+    this.value = convertDataToISO(this.activeParts);
 
     if (closeOverlay) {
       this.closeParentOverlay();

core/src/components/datetime/test/basic/e2e.ts

@@ -110,3 +110,41 @@ test('datetime:rtl: basic', async () => {
   const compare = await page.compareScreenshot();
   expect(compare).toMatchScreenshot();
 });
+
+
+describe('datetime: confirm date', () => {
+
+  test('should set the date value based on the selected date', async () => {
+
+    const page = await newE2EPage({
+      html: `
+        <button>Bind datetimeMonthDidChange event</button>
+        <ion-datetime value="2021-12-25T12:40:00.000Z"></ion-datetime>
+        <script type="module">
+          import { InitMonthDidChangeEvent } from '/src/components/datetime/test/utils/month-did-change-event.js';
+          document.querySelector('button').addEventListener('click', function() {
+            InitMonthDidChangeEvent();
+          });
+        </script>
+      `
+    });
+
+    const eventButton = await page.find('button');
+    await eventButton.click();
+
+    const buttons = await page.findAll('ion-datetime >>> .calendar-next-prev ion-button');
+
+    await buttons[1].click();
+
+    await page.waitForEvent('datetimeMonthDidChange');
+
+    await page.$eval('ion-datetime', async (el: any) => {
+      await el.confirm();
+    });
+
+    const value = await (await page.find('ion-datetime')).getProperty('value');
+
+    expect(value).toMatch('2021-12-25T12:40:00');
+  });
+
+});