feat(IndexBar): add scrollTo method (#7794)

src/index-bar/README.md

@@ -90,6 +90,14 @@ export default {
 | ------- | ------------------------------------- |
 | default | Anchor content, show index by default |
 
+### Methods
+
+Use [ref](https://v3.vuejs.org/guide/component-template-refs.html) to get IndexBar instance and call instance methods.
+
+| Name | Description | Attribute | Return value |
+| --- | --- | --- | --- |
+| scrollTo | scroll to target element | _index: number \| string_ | - |
+
 ### Less Variables
 
 How to use: [Custom Theme](#/en-US/theme).

src/index-bar/README.zh-CN.md

@@ -88,6 +88,14 @@ export default {
 | select            | 点击索引栏的字符时触发       | _index: number \| string_ |
 | change `v2.10.10` | 当前高亮的索引字符变化时触发 | _index: number \| string_ |
 
+### 方法
+
+通过 ref 可以获取到 IndexBar 实例并调用实例方法，详见[组件实例方法](#/zh-CN/advanced-usage#zu-jian-shi-li-fang-fa)。
+
+| 方法名   | 说明           | 参数                      | 返回值 |
+| -------- | -------------- | ------------------------- | ------ |
+| scrollTo | 滚动到指定锚点 | _index: number \| string_ | -      |
+
 ### IndexAnchor Slots
 
 | 名称    | 说明                             |

src/index-bar/index.js

@@ -19,6 +19,7 @@ import {
   useEventListener,
 } from '@vant/use';
 import { useTouch } from '../composables/use-touch';
+import { useExpose } from '../composables/use-expose';
 
 export const INDEX_BAR_KEY = 'vanIndexBar';
 
@@ -179,8 +180,7 @@ export default createComponent({
         );
       });
 
-    const scrollToElement = (element) => {
-      const { index } = element.dataset;
+    const scrollTo = (index) => {
       if (!index) {
         return;
       }
@@ -198,6 +198,11 @@ export default createComponent({
       }
     };
 
+    const scrollToElement = (element) => {
+      const { index } = element.dataset;
+      scrollTo(index);
+    };
+
     const onClick = (event) => {
       scrollToElement(event.target);
     };
@@ -223,6 +228,8 @@ export default createComponent({
       }
     };
 
+    useExpose({ scrollTo });
+
     return () => (
       <div ref={root} class={bem()}>
         <div

src/index-bar/test/index.legacy.js

@@ -163,3 +163,31 @@ test('should emit change event when active index changed', () => {
 
   Element.prototype.getBoundingClientRect = nativeRect;
 });
+
+test('scroll to target element', () => {
+  const onSelect = jest.fn();
+  mount({
+    template: `
+      <van-index-bar ref="anchorRef" @select="onSelect">
+        <van-index-anchor index="A" />
+        <van-index-anchor index="B" />
+        <van-index-anchor index="C" />
+        <van-index-anchor index="D" />
+        <van-index-anchor index="E" />
+        <van-index-anchor index="F" />
+        <van-index-anchor index="XXX" />
+      </van-index-bar>
+    `,
+    methods: {
+      onSelect,
+    },
+    mounted() {
+      this.$refs.anchorRef.scrollTo('C');
+    },
+  });
+
+  const fn = mockScrollIntoView();
+
+  expect(fn).toHaveBeenCalledTimes(1);
+  expect(onSelect).toHaveBeenCalledWith('C');
+});