create-indexeddatabase.js

function makePromise() {
    let resolve;
    let reject;
    const promise = new Promise((res, rej) => {
        resolve = res;
        reject = rej;
    });
    return { resolve, reject, promise };
}
/**
 * Creates objectStores in database called dbname using single transaction
 * @param {string} dbname
 * @param {CreateObjectStores} objectStores
 * @return The db version right now.
 * @returns number
 *
 * In IndexedDB, if you don't specify a key path or auto-increment option when creating an object store, the object store will use the following defaults:
 *
 *     - The key path will be null. This means that objects in the store will not have a key path, and you will need to provide a key explicitly when adding or updating objects.
 *     - The auto-increment option will be false. This means that objects in the store will not have an auto-incrementing key. If you provide a key when adding an object to the store, that key will be used as the key for the object.
 */
async function createIndexeddatabase(dbname, objectStores) {
    /* First find out if we need to update by opening the database without a version to get the current version and datastores */
    const { resolve, promise, reject } = makePromise();
    const request = indexedDB.open(dbname);
    request.onsuccess = (event) => resolve(event.target.result);
    request.onerror = reject;
    const db = await promise;
    db.onversionchange = db.close;
    let version = db.version;
    let to_create = [];
    if (objectStores instanceof Map) {
        for (const [name, options] of objectStores)
            if (!db.objectStoreNames.contains(name))
                to_create.push({ name, options });
    }
    else if (!(objectStores instanceof Map)) {
        for (const name in objectStores)
            if (!db.objectStoreNames.contains(name))
                to_create.push({ name, options: objectStores[name] });
    }
    /* Create the new database if needed */
    {
        const { promise, reject, resolve } = makePromise();
        if (to_create.length) {
            // true if we need to update
            const request = indexedDB.open(dbname, ++version); // closes other db
            request.onupgradeneeded = (event) => {
                const db = event.target.result;
                for (const { name, options } of to_create)
                    db.createObjectStore(name, options);
            };
            request.onerror = reject;
            request.onsuccess = (event) => {
                const db = event.target.result;
                resolve(db.version);
                db.close();
            };
            return promise;
        }
        resolve(db.version);
        db.close();
        return promise;
    }
}
export default createIndexeddatabase;