fix(input): ion-input accepts any string value (#24606)

Resolves #19884

core/src/components/input/input.tsx

@@ -231,6 +231,17 @@ export class Input implements ComponentInterface {
    */
   @Watch('value')
   protected valueChanged() {
+    if (this.nativeInput) {
+      /**
+       * Assigning the native input's value on attribute
+       * value change, allows `ionInput` implementations
+       * to override the control's value.
+       *
+       * Used for patterns such as input trimming (removing whitespace),
+       * or input masking.
+       */
+      this.nativeInput.value = this.getValue();
+    }
     this.emitStyle();
     this.ionChange.emit({ value: this.value == null ? this.value : this.value.toString() });
   }

core/src/components/input/test/masking/e2e.ts

@@ -0,0 +1,20 @@
+import { newE2EPage } from '@stencil/core/testing';
+
+test('input: masking', async () => {
+  const page = await newE2EPage({
+    url: '/src/components/input/test/masking?ionic:_testing=true'
+  });
+
+  const inputTrimmed = await page.find('#inputTrimmed');
+
+  await inputTrimmed.click();
+
+  await page.keyboard.type('S p a c e s');
+
+  const currentValue = await page.$eval('#inputTrimmed', (el: any) => {
+    return el.value;
+  });
+
+  expect(currentValue).toEqual('Spaces');
+
+});

core/src/components/input/test/masking/index.html

@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<html lang="en" dir="ltr">
+
+<head>
+  <meta charset="UTF-8">
+  <title>Input - Masking</title>
+  <meta name="viewport"
+    content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no">
+  <link href="../../../../../css/ionic.bundle.css" rel="stylesheet">
+  <link href="../../../../../scripts/testing/styles.css" rel="stylesheet">
+  <script src="../../../../../scripts/testing/scripts.js"></script>
+  <script nomodule src="../../../../../dist/ionic/ionic.js"></script>
+  <script type="module" src="../../../../../dist/ionic/ionic.esm.js"></script>
+</head>
+
+<body>
+  <ion-app>
+    <ion-header>
+      <ion-toolbar>
+        <ion-title>Input - Masking</ion-title>
+      </ion-toolbar>
+    </ion-header>
+    <ion-content>
+      <ion-item>
+        <ion-label position="stacked">Input with trimming</ion-label>
+        <ion-input id="inputTrimmed" placeholder="Trimmed Input" />
+      </ion-item>
+    </ion-content>
+
+    <script>
+      document
+        .getElementById('inputTrimmed')
+        .addEventListener('ionInput', e => {
+          e.target.value = e.target.value.trim();
+        });
+    </script>
+  </ion-app>
+</body>
+
+</html>