fix(Slider): should update startValue when the slider is clicked (#11904)

packages/vant/src/slider/Slider.tsx

@@ -133,6 +133,15 @@ export default defineComponent({
       return addNumber(min, diff);
     };
 
+    const updateStartValue = () => {
+      const current = props.modelValue;
+      if (isRange(current)) {
+        startValue = current.map(format) as NumberRange;
+      } else {
+        startValue = format(current);
+      }
+    };
+
     const handleRangeValue = (value: NumberRange) => {
       // 设置默认值
       const left = value[0] ?? Number(props.min);
@@ -164,6 +173,8 @@ export default defineComponent({
         return;
       }
 
+      updateStartValue();
+
       const { min, reverse, vertical, modelValue } = props;
       const rect = useRect(root);
 
@@ -204,12 +215,7 @@ export default defineComponent({
 
       touch.start(event);
       current = props.modelValue;
-
+      updateStartValue();
-      if (isRange(current)) {
-        startValue = current.map(format) as NumberRange;
-      } else {
-        startValue = format(current);
-      }
 
       dragStatus.value = 'start';
     };

packages/vant/src/slider/test/index.spec.ts

@@ -182,6 +182,8 @@ test('should emit "update:modelValue" event after clicking vertical slider', ()
 });
 
 test('should not emit change event when value not changed', async () => {
+  const restoreMock = mockRect();
+
   const wrapper = mount(Slider, {
     props: {
       modelValue: 50,
@@ -196,8 +198,16 @@ test('should not emit change event when value not changed', async () => {
   await wrapper.setProps({ modelValue: 100 });
   trigger(button, 'touchstart');
   trigger(wrapper, 'click', 100, 0);
-
   expect(wrapper.emitted('change')).toHaveLength(1);
+
+  trigger(wrapper, 'click', 50, 0);
+  expect(wrapper.emitted('change')).toHaveLength(2);
+
+  await wrapper.setProps({ modelValue: 50 });
+  trigger(wrapper, 'click', 100, 0);
+  expect(wrapper.emitted('change')).toHaveLength(3);
+
+  restoreMock();
 });
 
 // https://github.com/vant-ui/vant/issues/8889