docs: 修复导出组件示例报错 close #3059

[lijinke666]

👀 PR includes

🔧 Chore

• Test case
• Docs / demos update
• CI / workflow
• Release version
• Other ()

📝 Description

close #3059

🖼️ Screenshot

Before	After
❌	✅

🔗 Related issue link

🔍 Self-Check before the merge

• Add or update relevant docs.
• Add or update relevant demos.
• Add or update test case.
• Add or update relevant TypeScript definitions.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
antvis-s2	❌ Failed (Inspect)			Jan 2, 2025 9:18am

[github-actions]

你好 @lijinke666，非常感谢你的贡献.
为了让代码更健壮, 请根据 贡献指南 补充相应单元测试 (文档改动或其他特殊场景除外), 如果有 API 改动, 请修改 相应的文档.
同时请检查 lint 和 test 相关 CI 是否通过, 如果失败, 请点击 [Details] 按钮查看, 并根据日志修复.

Hello, @lijinke666, Thanks for your contribution. In order to make the code more robust, please add the corresponding unit tests, and update the docs if there are API changes.
At the same time, please check whether the CI related to lint and test passes. If the CI fails, please click [Details] button to check and repair according to the log.

[petercat-assistant]

Walkthrough

此PR修复了导出组件示例中的错误，主要通过在React组件中使用React.useState和onMounted来获取和保存表格实例，确保组件正常更新。此更改解决了异步渲染的问题，确保在onMounted后获取最新的实例。

Changes

文件	概要
s2-site/docs/manual/advanced/get-instance.zh.md	添加了关于如何在React组件中使用React.useState和onMounted获取表格实例的说明。
s2-site/examples/react-component/export/demo/export-strategy.tsx	修改了示例代码，使用React.useState和onMounted代替React.useRef来获取表格实例。
s2-site/examples/react-component/export/demo/export.tsx	同样修改了示例代码，使用React.useState和onMounted代替React.useRef来获取表格实例。

[petercat-assistant]

确保在onMounted中获取实例时，组件的生命周期已经准备好，以避免潜在的异步问题。

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.77%. Comparing base (ecdc9c8) to head (8d877a4).
Report is 585 commits behind head on next.

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #3063      +/-   ##
==========================================
  Coverage   75.77%   75.77%              
==========================================
  Files         257       51     -206     
  Lines       11994     1490   -10504     
  Branches     2464      284    -2180     
==========================================
- Hits         9088     1129    -7959     
+ Misses       1398      210    -1188     
+ Partials     1508      151    -1357     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

Size Change: 0 B

Total Size: 619 kB

ℹ️ View Unchanged

Filename	Size
./packages/s2-core/dist/s2-extends.min.js	154 kB
./packages/s2-core/dist/s2.min.css	581 B
./packages/s2-core/dist/s2.min.js	257 kB
./packages/s2-react-components/dist/s2-react-components.min.css	2.55 kB
./packages/s2-react-components/dist/s2-react-components.min.js	124 kB
./packages/s2-react/dist/s2-react.min.css	1.74 kB
./packages/s2-react/dist/s2-react.min.js	38.3 kB
./packages/s2-vue/dist/s2-vue.min.css	2.05 kB
./packages/s2-vue/dist/s2-vue.min.js	38.3 kB

_{compressed-size-action}