finaly i find the good code for node.js use express js in this page : https://shopify.dev/docs/apps/auth/embedded-auth-tutorial?extension=javascript
i copy the code and i integrate im my app final ywork fine 
Topic summary
A developer encountered an authentication callback issue specifically in incognito/no-cookie mode, while normal browsing mode worked correctly. The setup involves:
Tech Stack:
- Backend: Node.js with Express
- Frontend: React for embedded app
Resolution:
The issue was resolved by implementing the correct authentication code from Shopify’s official embedded auth tutorial for JavaScript apps (https://shopify.dev/docs/apps/auth/embedded-auth-tutorial?extension=javascript). After copying and integrating this code, the app now functions properly.
Status: Resolved - the developer successfully fixed the authentication flow by following Shopify’s recommended implementation pattern for embedded apps.