[new feature] IndexBar: add select event

packages/index-bar/en-US.md

@@ -68,6 +68,12 @@ export default {
 |------|------|------|------|
 | index | Index | `String | Number` | - |
 
+### IndexBar Events
+
+| Event | Description | Arguments |
+|------|------|------|
+| select | Triggered when select index | index |
+
 ### IndexAnchor Slots
 
 | Name | Description |

packages/index-bar/index.js

@@ -60,6 +60,7 @@ export default sfc({
       const match = this.children.filter(item => String(item.index) === index);
       if (match[0]) {
         match[0].scrollIntoView();
+        this.$emit('select', match[0].index);
       }
     },
 

packages/index-bar/test/index.spec.js

@@ -26,30 +26,40 @@ test('custom anchor text', () => {
 });
 
 test('click and scroll to anchor', () => {
+  const onSelect = jest.fn();
   const wrapper = mount({
     template: `
-      <van-index-bar>
+      <van-index-bar @select="onSelect">
         <van-index-anchor index="A" />
         <van-index-anchor index="B" />
       </van-index-bar>
-    `
+    `,
+    methods: {
+      onSelect
+    }
   });
 
   const fn = mockScrollIntoView();
   const indexes = wrapper.findAll('.van-index-bar__index');
   indexes.at(0).trigger('click');
+
   expect(fn).toHaveBeenCalledTimes(1);
+  expect(onSelect).toHaveBeenCalledWith('A');
 });
 
 test('touch and scroll to anchor', () => {
+  const onSelect = jest.fn();
   const wrapper = mount({
     template: `
-      <van-index-bar>
+      <van-index-bar @select="onSelect">
         <van-index-anchor index="A" />
         <van-index-anchor index="B" />
         <van-index-anchor index="XXX" />
       </van-index-bar>
-    `
+    `,
+    methods: {
+      onSelect
+    }
   });
 
   const fn = mockScrollIntoView();
@@ -82,4 +92,5 @@ test('touch and scroll to anchor', () => {
   trigger(sidebar, 'touchmove', 0, 400);
   trigger(sidebar, 'touchend', 0, 400);
   expect(fn).toHaveBeenCalledTimes(1);
+  expect(onSelect).toHaveBeenCalledWith('B');
 });

packages/index-bar/zh-CN.md

@@ -72,6 +72,12 @@ export default {
 |------|------|------|------|------|
 | index | 索引字符 | `String | Number` | - | - |
 
+### IndexBar Events
+
+| 事件名 | 说明 | 回调参数 |
+|------|------|------|
+| select | 选中字符时触发 | index: 索引字符 |
+
 ### IndexAnchor Slots
 
 | 名称 | 说明 |