Common Mistakes That Break SeaText AI Local Storage in Single Page Applications (SPAs)

The most common causes of SeaText AI local storage failure in single page applications (SPAs) are serving the app over HTTP, using private or incognito browsing with storage disabled, running storage blockers, and using a cross-origin or domain setup that the script cannot handle. These issues prevent the script from persisting the ID it stores in localStorage.

The SeaText AI documentation for SPAs lists localStorage as an additional consideration. The script stores an ID in localStorage. Your application needs permission to access and use localStorage. If your SPA interacts with multiple domains, check that the script is compatible and does not face cross-origin issues.

Why SeaText AI Uses Local Storage in SPAs

SPAs load one HTML page and update the DOM as users move through the app. They do not rely on full page reloads. This makes client-side storage useful for keeping small values across routes.

The SeaText AI SPA snippet uses the async attribute. That helps the script load without blocking page render. The documentation also says the script stores an ID in local storage. That ID is the only SeaText-specific storage detail described in the official SPA guide.

Why does this matter? If localStorage is unavailable, the script cannot write or read that ID. The app may restart translation work on every route change. Returning visitors may not get the same state.

Top 4 Common Mistakes That Break Local Storage Access

These are the most frequent environment and configuration issues that stop SeaText AI from using localStorage in SPAs.

• Serving the SPA over HTTP instead of HTTPS
  Modern browsers treat localStorage as part of a secure context. Public sites served over HTTP are not secure contexts, so localStorage access is blocked. Localhost is usually exempt for local development. Production SPAs should always use HTTPS.
• Private browsing or storage disabled
  Some privacy modes block localStorage entirely. Others allow it during the session but clear it when the window closes. Users can also disable site data in browser settings. If localStorage is not available, the script cannot store the ID.
• Third-party cookie and storage blockers
  Privacy extensions and built-in tracking protection may block localStorage. This often happens when a page or script is classified as third-party. The result can look like a script error, but the real problem is denied storage access.
• Cross-origin or domain configuration problems
  The official guide says to check cross-origin behavior when a SPA interacts with multiple domains. A SPA may be served from one origin and call APIs or load resources from another. In that setup, storage and script access may be blocked. Review each domain the SPA uses. Make sure the SeaText AI script is compatible with that environment.

Step-by-Step Diagnosis Order

Follow this order to find the root cause quickly. Start with the easiest checks.

1. Open the browser console. Use Developer Tools and look for localStorage, security, or CORS errors.
2. Check the URL. Confirm the site is served over HTTPS. If you see HTTP, that is likely the problem.
3. Test in a normal window with extensions off. Open a standard browser session and disable ad blockers and privacy extensions. If localStorage works, an extension or privacy setting is blocking it.
4. Run a quick localStorage diagnostic. Paste this snippet into the browser console:

   const key = 'local-storage-diagnostic';
   try {
     localStorage.setItem(key, 'ok');
     const value = localStorage.getItem(key);
     localStorage.removeItem(key);
     console.log('localStorage test passed:', value);
   } catch (error) {
     console.error('localStorage test failed:', error);
   }
   

   Check the Console tab for "localStorage test passed" or "localStorage test failed".
5. Check cross-origin behavior. If the SPA interacts with multiple domains, test the SeaText AI script on each domain. Look for blocked requests or storage errors in the Network and Console tabs.

Corrective Actions for Each Mistake

• Move to HTTPS. Use HTTPS for every public deployment. For local development, test on http://localhost, which is exempt from the secure context restriction in most browsers.
• Handle private-mode limits. Test in a regular browser window first. If users see issues in private mode, ask them to check their site-data settings. You cannot override a user's privacy choice.
• Work with storage blockers. Ask users to whitelist your domain in privacy extensions. For your own tests, disable extensions and confirm that localStorage works. If it works, an extension is the cause.
• Fix cross-origin or domain issues. Map every domain the SPA uses. Test the SeaText AI script on each domain. Look for CORS, mixed-content, or storage errors in the console. If storage needs to be shared across origins, implement your own server-side persistence at the application level. The SeaText docs do not describe a built-in shared storage context.

Key Facts About SeaText AI Local Storage in SPAs

Limitations of SeaText AI Local Storage

• localStorage is scoped to one origin. Data on one scheme, host, or port is not automatically available on another.
• Browsers can clear localStorage when users clear site data.
• Private modes can block or discard localStorage.
• Extensions can deny storage access.
• The official SeaText SPA docs describe an ID only. Do not assume the script stores language, version, or session values.
• Cross-origin setups require testing. A script that works on one domain may be blocked on another.
• For durable persistence, use server-side storage in your own application. SeaText docs do not describe syncing preferences to a backend or offering a shared storage context.

Frequently Asked Questions

1. Why does my SeaText AI translation reset on route changes?
   This usually means localStorage is blocked. Check HTTPS, private mode, storage blockers, and browser console errors. Run the diagnostic snippet above.
2. What data does SeaText AI store in localStorage?
   The official SPA guide says the script stores an ID. It does not list language, version, or session fields. If your app needs those values, store them through your own code or backend.
3. Does localStorage work across subdomains?
   Not by default. Each origin has its own localStorage. If your SPA interacts with multiple domains, test cross-origin compatibility. For shared data, use your own server-side persistence.
4. How do I check whether the SeaText AI script writes the ID?
   Open Developer Tools, go to the Application tab, and open Local Storage. Look for the stored ID after the script loads. If it is missing, check permissions and cross-origin errors.
5. Do private mode or ad blockers always break SeaText AI local storage?
   No. Some private modes allow storage during the session, and not all extensions block storage. The safe test is to use a normal window with extensions off.
6. What should I do if the script works on one domain but not another?
   Review the origin and cross-origin setup. Test each domain separately, check the browser console, and confirm that the SeaText AI script is compatible with every domain the SPA touches.