How do you handle version changes in IndexedDB?

Question

Ponu Maurya · Answer

Handling version changes in IndexedDB is a critical part of managing schema upgrades (like adding new object stores or indexes).
How Versioning Works in IndexedDB
Every IndexedDB database has a version number (default is 
1). A version change triggers the onupgradeneeded event. You can only modify the
database structure (create/delete object stores, indexes, etc.) inside this event.
Version Change Flow
const request = indexedDB.open("MyDatabase", 2); // Version 2 triggers upgrade
request.onupgradeneeded = function (event) {
    const db = event.target.result;
    const oldVersion = event.oldVersion;
    const newVersion = event.newVersion;
    console.log(`Upgrading from version ${oldVersion} to ${newVersion}`);
    if (oldVersion andlt; 1) {
        const store = db.createObjectStore("users", { keyPath: "id" });
        store.createIndex("name", "name", { unique: false });
    }
    if (oldVersion andlt; 2) {
        const store = db.transaction.objectStore("users");
        store.createIndex("email", "email", { unique: true });
    }
};
request.onsuccess = function (event) {
    const db = event.target.result;
    console.log("Database opened successfully.");
};
request.onerror = function (event) {
    console.error("Database error:", event.target.error);
};
Key Points
Feature
Explanation
indexedDB.open(name, version)
Pass a higher version number to trigger schema changes.
onupgradeneeded
Only place you can create/remove object stores and indexes.
event.oldVersion
The version you’re upgrading from.
event.newVersion
The version you’re upgrading to.
Safe Upgrades
Always use version checks like if (oldVersion andlt; x) to support multi-step upgrades.
Best Practice
Always increment the version number when changing schema.Never use put/add/delete 
inside onupgradeneeded unless necessary — structure only.Use feature flags or version guards to keep upgrades backward-compatible.

Feature	Explanation
`indexedDB.open(name, version)`	Pass a higher version number to trigger schema changes.
`onupgradeneeded`	Only place you can create/remove object stores and indexes.
`event.oldVersion`	The version you’re upgrading from.
`event.newVersion`	The version you’re upgrading to.
Safe Upgrades	Always use version checks like `if (oldVersion < x)` to support multi-step upgrades.

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How do you handle version changes in IndexedDB?

Ponu Maurya

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1 Answers

How Versioning Works in IndexedDB

Version Change Flow

Key Points

Best Practice

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