feat(CollapseItem): add lazy-render prop (#10270)

packages/vant/docs/markdown/changelog.en-US.md

@@ -20,7 +20,7 @@ Vant follows [Semantic Versioning 2.0.0](https://semver.org/lang/zh-CN/).
 
 `2022-02-07`
 
-- Vant 3 对应的 npm tag 切换为 `latest`
+- switch default npm tag to `latest`
 
 ### [v3.4.3](https://github.com/compare/v3.4.2...v3.4.3)
 

packages/vant/docs/markdown/changelog.zh-CN.md

@@ -20,7 +20,7 @@ Vant 遵循 [Semver](https://semver.org/lang/zh-CN/) 语义化版本规范。
 
 `2022-02-07`
 
-- switch default npm tag to `latest`
+- Vant 3 对应的 npm tag 切换为 `latest`
 
 ### [v3.4.3](https://github.com/compare/v3.4.2...v3.4.3)
 

packages/vant/src/collapse-item/CollapseItem.tsx

@@ -35,6 +35,7 @@ const collapseItemProps = extend({}, cellSharedProps, {
   isLink: truthProp,
   disabled: Boolean,
   readonly: Boolean,
+  lazyRender: truthProp,
 });
 
 export type CollapseItemProps = ExtractPropTypes<typeof collapseItemProps>;
@@ -62,7 +63,7 @@ export default defineComponent({
     const expanded = computed(() => parent.isExpanded(name.value));
 
     const show = ref(expanded.value);
-    const lazyRender = useLazyRender(show);
+    const lazyRender = useLazyRender(() => show.value || !props.lazyRender);
 
     const onTransitionEnd = () => {
       if (!expanded.value) {

packages/vant/src/collapse/README.md

@@ -138,6 +138,7 @@ export default {
 | disabled | Whether to disabled collapse | _boolean_ | `false` |
 | readonly `v3.0.12` | Whether to be readonly | _boolean_ | `false` |
 | is-link | Whether to show link icon | _boolean_ | `true` |
+| lazy-render `v3.4.5` | Whether to lazy render util opened | _boolean_ | `true` |
 | title-class | Title className | _string_ | - |
 | value-class | Value className | _string_ | - |
 | label-class | Label className | _string_ | - |

packages/vant/src/collapse/README.zh-CN.md

@@ -154,6 +154,7 @@ export default {
 | is-link | 是否展示标题栏右侧箭头并开启点击反馈 | _boolean_ | `true` |
 | disabled | 是否禁用面板 | _boolean_ | `false` |
 | readonly `v3.0.12` | 是否为只读状态，只读状态下无法操作面板 | _boolean_ | `false` |
+| lazy-render `v3.4.5` | 是否在首次展开时才渲染面板内容 | _boolean_ | `true` |
 | title-class | 左侧标题额外类名 | _string_ | - |
 | value-class | 右侧内容额外类名 | _string_ | - |
 | label-class | 描述信息额外类名 | _string_ | - |