fix(Calendar): content disappeared when hiding (#10910)

* fix(Calendar): content disappeared when hiding

* chore: add comment

* chore: upd

packages/vant/src/calendar/Calendar.tsx

@@ -185,10 +185,6 @@ export default defineComponent({
       const months: Date[] = [];
       const cursor = new Date(props.minDate);
 
-      if (props.lazyRender && !props.show && props.poppable) {
-        return months;
-      }
-
       cursor.setDate(1);
 
       do {
@@ -299,7 +295,9 @@ export default defineComponent({
           props.type === 'single'
             ? (currentDate.value as Date)
             : (currentDate.value as Date[])[0];
-        scrollToDate(targetDate);
+        if (isDate(targetDate)) {
+          scrollToDate(targetDate);
+        }
       } else {
         raf(onScroll);
       }

packages/vant/src/composables/use-height.ts

@@ -1,5 +1,6 @@
 import { useRect } from '@vant/use';
 import { Ref, ref, onMounted, nextTick } from 'vue';
+import { onPopupReopen } from './on-popup-reopen';
 
 export const useHeight = (
   element: Element | Ref<Element | undefined>,
@@ -25,5 +26,11 @@ export const useHeight = (
     }
   });
 
+  // The result of useHeight might be 0 when the popup is hidden,
+  // so we need to reset the height when the popup is reopened.
+  // IntersectionObserver is a better solution, but it is not supported by legacy browsers.
+  // https://github.com/vant-ui/vant/issues/10628
+  onPopupReopen(() => nextTick(setHeight));
+
   return height;
 };