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Home Interviews Demonstrate how to use IndexedDB with Promises. – MindStick
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1 Answers

Jiva Ram
Jiva Ram 30 Jun 2025
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Here’s a clean and modern way to use IndexedDB with Promises, which makes asynchronous code much easier to read and maintain compared to traditional callback-style.

IndexedDB with Promises – Full Example

This example shows how to:

  • Open a database
  • Create an object store (if not exists)
  • Add records
  • Get all records

1. Helper Function: Open Database with Schema Setup

function openDatabase(dbName, storeName) {
    return new Promise((resolve, reject) => {
        const request = indexedDB.open(dbName, 1); // version 1

        request.onupgradeneeded = (event) => {
            const db = event.target.result;

            if (!db.objectStoreNames.contains(storeName)) {
                db.createObjectStore(storeName, { keyPath: 'id', autoIncrement: true });
            }
        };

        request.onsuccess = (event) => {
            resolve(event.target.result);
        };

        request.onerror = (event) => {
            reject(`DB open error: ${event.target.errorCode}`);
        };
    });
}

2. Add a Record

function addRecord(db, storeName, data) {
    return new Promise((resolve, reject) => {
        const transaction = db.transaction(storeName, 'readwrite');
        const store = transaction.objectStore(storeName);

        const request = store.add(data);

        request.onsuccess = () => resolve(request.result);
        request.onerror = (event) => reject(`Add error: ${event.target.errorCode}`);
    });
}

3. Get All Records

function getAllRecords(db, storeName) {
    return new Promise((resolve, reject) => {
        const transaction = db.transaction(storeName, 'readonly');
        const store = transaction.objectStore(storeName);

        const request = store.getAll();

        request.onsuccess = () => resolve(request.result);
        request.onerror = (event) => reject(`GetAll error: ${event.target.errorCode}`);
    });
}

4. Putting It All Together

(async () => {
    const dbName = 'MyDB';
    const storeName = 'Users';

    try {
        const db = await openDatabase(dbName, storeName);

        await addRecord(db, storeName, { name: 'Alice', age: 25 });
        await addRecord(db, storeName, { name: 'Bob', age: 30 });

        const users = await getAllRecords(db, storeName);
        console.log('All users:', users);
    } catch (error) {
        console.error('IndexedDB error:', error);
    }
})();

Summary

  1. Promises help avoid nested callbacks.
  2. You can wrap indexedDB operations in Promise-based helpers.
  3. Use async/await for cleaner code flow.
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