Preview and testing
How the live preview works for Apps and Web Apps, and what behaves differently there.
Apps
Apps run in Expo's official web player, shown on a phone frame. The first load can take 10–20 seconds while Expo bundles your code. Press Reload above the preview to restart it.
To try an App on a real phone, download it (see Exporting your code) and open it with Expo Go.
Web Apps
Web Apps run in a browser frame. Use the desktop / tablet / phone buttons to check responsive layouts at real widths.
For your safety, the preview runs in a sandbox: it can't read Appfully's cookies or your account. A few browser features behave differently there:
| Feature | In the preview | In your exported or published app |
|---|---|---|
| Saving data (localStorage) | Works, but resets when the preview reloads | Real, persistent storage |
| Page URLs (history) | Kept as a #hash; the page doesn't navigate | Normal URLs |
| IndexedDB | Not available (reports "unsupported") | Available |
| Offline / service workers | Ignored | Available |
| Copy to clipboard | Works after a click | Works |
| Links to other sites | Open in a new tab | Normal |
| Links to pages that don't exist | Show a short note instead of navigating | Normal |
| Forms | Stay on the page | Whatever your code does |
The Code tab
Switch to Code to read the full App.tsx (and watch it stream in during a build). Use Copy to grab it.
Testing checklist
- Click through every screen and button.
- Add, edit and delete some data, then reload to see what persists.
- Web Apps: check phone width for overflowing text and tap targets.
- Apps: check that text fits on a small phone and nothing hides under the notch.
Related articles
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