feat(Field): add formatter prop (#5534)

src/field/test/__snapshots__/demo.spec.js.snap

@@ -115,6 +115,16 @@ exports[`renders demo correctly 1`] = `
       </div>
     </div>
   </div>
+  <div>
+    <div class="van-cell-group van-hairline--top-bottom">
+      <div class="van-cell van-field">
+        <div class="van-cell__title van-field__label"><span>文本</span></div>
+        <div class="van-cell__value">
+          <div class="van-field__body"><input type="text" placeholder="格式化输入内容" class="van-field__control"></div>
+        </div>
+      </div>
+    </div>
+  </div>
   <div>
     <div class="van-cell-group van-hairline--top-bottom">
       <div class="van-cell van-field">

src/field/test/index.spec.js

@@ -262,3 +262,21 @@ test('arrow-direction prop', () => {
   });
   expect(wrapper).toMatchSnapshot();
 });
+
+test('formatter prop', () => {
+  const wrapper = mount(Field, {
+    propsData: {
+      value: 'abc123',
+      formatter: (value) => value.replace(/\d/g, '')
+    }
+  });
+
+  const input = wrapper.find('input');
+
+  input.trigger('input');
+  expect(wrapper.emitted('input')[0][0]).toEqual('abc');
+
+  input.element.value = '123efg';
+  input.trigger('input');
+  expect(wrapper.emitted('input')[1][0]).toEqual('efg');
+});