What happens if a user disables storage or clears site data?

Question

ICSM Computer · Answer

When a user disables storage or clears site data, your
IndexedDB data can be lost or made inaccessible, depending on the action and browser.
Here’s a breakdown of what happens:
1. User Clears Site Data (via browser settings)
When a user clears site data (cookies, local storage, cache, etc.), this typically includes:
Storage Type
Is it Cleared?
Cookies
✅ Yes
LocalStorage
✅ Yes
IndexedDB
✅ Yes
Cache Storage
✅ Yes
Service Workers
✅ Yes
Impact on IndexedDB:
All databases and object stores are deleted
Next time the app loads, indexedDB.open() will behave like the DB never existed (i.e., version = 0)You will need to recreate schema in onupgradeneeded
2. User Disables Storage (Privacy/Incognito Mode)
Some browsers (especially Safari) restrict or block IndexedDB in private mode:
Browser
Behavior in Private Mode
Chrome
✅ Works normally
Firefox
✅ Works normally
Safari (iOS/macOS)
❌ Fails or silently blocks IndexedDB
Brave
⚠️ May block or isolate per-session
Impact:
indexedDB.open() may:
Fail silentlyThrow a QuotaExceededErrorReturn undefined or nullAny attempt to store or read data will not persist or may crash
3. Automatic Eviction by the Browser
Browsers may automatically delete data when:
Device is low on space (especially mobile)The site is inactive for a long timeStorage is non-persistent (default behavior)
To reduce risk:
You can request persistent storage (only works in supported browsers):
if (navigator.storage andand navigator.storage.persist) {
    navigator.storage.persist().then(granted =andgt; {
        console.log(granted ? "Persistent storage granted" : "Not granted");
    });
}
Best Practices to Handle This
Tip
Why
Use feature detection (if (!window.indexedDB))
Avoid crashing on unsupported devices
Handle onerror on open, get, put
Catch failures gracefully
Use onupgradeneeded to recreate schema if DB is gone
Allows safe recovery
Inform users if data was cleared
Improves user experience
Use navigator.storage.persist()
Reduce risk of auto-deletion
and Detect if Data is Lost
indexedDB.open("MyDB").onsuccess = function (event) {
    const db = event.target.result;
    if (!db.objectStoreNames.contains("users")) {
        // Data likely cleared
        alert("App data has been reset or cleared.");
    }
};
Summary
Action
Result for IndexedDB
User clears browser/site data
❌ All IndexedDB data is deleted
Private/incognito mode
⚠️ IndexedDB may be disabled or wiped
Automatic eviction
⚠️ Data may be deleted silently
Persistent storage requested
✅ More likely to survive cleanup

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What happens if a user disables storage or clears site data?

ICSM Computer

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1 Answers

1. User Clears Site Data (via browser settings)

Impact on IndexedDB:

2. User Disables Storage (Privacy/Incognito Mode)

Impact:

3. Automatic Eviction by the Browser

To reduce risk:

Best Practices to Handle This

Detect if Data is Lost

Summary

Liked By

Storage Type	Is it Cleared?
Cookies	✅ Yes
LocalStorage	✅ Yes
IndexedDB	✅ Yes
Cache Storage	✅ Yes
Service Workers	✅ Yes

Browser	Behavior in Private Mode
Chrome	✅ Works normally
Firefox	✅ Works normally
Safari (iOS/macOS)	❌ Fails or silently blocks IndexedDB
Brave	⚠️ May block or isolate per-session

Tip	Why
Use feature detection (`if (!window.indexedDB)`)	Avoid crashing on unsupported devices
Handle `onerror` on `open`, `get`, `put`	Catch failures gracefully
Use `onupgradeneeded` to recreate schema if DB is gone	Allows safe recovery
Inform users if data was cleared	Improves user experience
Use `navigator.storage.persist()`	Reduce risk of auto-deletion

Action	Result for IndexedDB
User clears browser/site data	❌ All IndexedDB data is deleted
Private/incognito mode	⚠️ IndexedDB may be disabled or wiped
Automatic eviction	⚠️ Data may be deleted silently
Persistent storage requested	✅ More likely to survive cleanup