feat(Calendar): add month-show event (#6292)

src/calendar/README.md

@@ -291,6 +291,7 @@ Following props are supported when the type is multiple
 | opened `v2.5.2` | Triggered when opened Popup | - |
 | closed `v2.5.2` | Triggered when closed Popup | - |
 | unselect `v2.7.2` | Triggered when unselect date when type is multiple | _value: Date_ |
+| month-show `v2.8.2` | Triggered when a month enters the visible area | _{ date: Date, title: string }_ |
 
 ### Slots
 

src/calendar/README.zh-CN.md

@@ -294,7 +294,8 @@ export default {
 | close `v2.5.2` | 关闭弹出层时触发 | - |
 | opened `v2.5.2` | 打开弹出层且动画结束后触发 | - |
 | closed `v2.5.2` | 关闭弹出层且动画结束后触发 | - |
-| unselect `v2.7.2` | 当 Canlendar 的 `type` 为 `multiple` 时，取消选中日期时触发 | _value: Date_ |
+| unselect `v2.7.2` | 当日历组件的 `type` 为 `multiple` 时，取消选中日期时触发 | _value: Date_ |
+| month-show `v2.8.2` | 当某个月份进入可视区域时触发 | _{ date: Date, title: string }_ |
 
 ### Slots
 

src/calendar/index.js

@@ -253,6 +253,13 @@ export default createComponent({
           currentMonth = months[i];
         }
 
+        if (!months[i].visible && visible) {
+          this.$emit('month-show', {
+            date: months[i].date,
+            title: months[i].title,
+          });
+        }
+
         months[i].visible = visible;
         height += heights[i];
       }

src/calendar/test/prop.spec.js

@@ -180,3 +180,14 @@ test('lazy-render prop', () => {
 
   expect(wrapper).toMatchSnapshot();
 });
+
+test.only('month-show event', async () => {
+  const wrapper = mount(Calendar, {
+    propsData: {
+      value: true,
+    },
+  });
+  await later();
+
+  expect(wrapper.emitted('month-show')).toBeTruthy();
+});