Versioned asset rollback versus migration‑script rollback: handling cached Template7 templates after a failed upgrade

Answer to the Core Question

When a Framework7 upgrade fails, only a migration‑script that explicitly calls Template7.clearCache() guarantees deterministic handling of compiled templates. Redirecting the router to a previous asset bundle does not touch the in‑memory cache; stale templates can still be reused unless the cache is cleared.

Confirmed Facts

• The Template7.clearCache() method (available from Framework7 v6.x) removes all compiled templates from the internal cache.
• Calling Template7.clearCache() after the old JavaScript bundle has loaded guarantees that subsequent renders compile fresh templates from the restored assets.
• Asset‑bundle redirection alone does not clear the cache; if the browser keeps the old bundle in memory, the same compiled templates may be reused.
• If a Service Worker is active, it may continue to serve the upgraded bundle until the Service Worker cache is also invalidated.

Steps for Migration‑Script Rollback

1. Load the previous bundle – ensure the old JavaScript files are fetched (e.g., by redirecting the router or by modifying the src attributes of the <script> tags).
2. Wait for the old bundle to execute – only after Framework7 is initialized can you safely clear the cache.
3. Clear the Template7 cache:

   if (typeof Template7 !== 'undefined' && Template7.clearCache) {
     Template7.clearCache();
   }
   

4. Optionally force a full page reload to guarantee that no stale JavaScript is still executing:

   window.location.reload(true); // true forces reload from network
   

5. Verify – open the console, type Template7.cache to confirm it’s empty, and check that rendering logs show new template compilations.

Steps for Asset‑Bundle Redirection (Non‑Deterministic)

1. Redirect the router to the old asset URL.
2. After the old bundle loads, manually call Template7.clearCache() as shown above.
3. If a Service Worker is present, run caches.keys().then(keys => keys.forEach(k => caches.delete(k))) or unregister the Service Worker to purge stale bundles.
4. Reload the page to ensure the old JavaScript is executed from scratch.

Missing Diagnostic Detail

To decide whether the Service Worker step is necessary, please confirm whether your application registers a Service Worker during initialization.

Practical Verification

• Open the console after rollback and run Template7.cache – it should show no entries.
• Trigger a UI action that renders a template; the console should log a compilation message.
• Compare the rendered markup before and after clearing the cache to ensure no stale HTML is present.