IndexedDB Promised
This is a tiny library that mirrors IndexedDB, but replaces the weird IDBRequest
objects with promises, plus a couple of other small changes.
Installation
If you're using Rollup/Webpack or similar:
npm install idb
Then in your JS:
import { openDb, deleteDb } from 'idb';
await openDb(…);
Or include the script as it is, and idb
will exist on the global scope.
Examples
Keyval Store
This is very similar to localStorage
, but async. If this is all you need, you may be interested in idb-keyval, you can always upgrade to this library later.
const dbPromise = openDb('keyval-store', 1, upgradeDB => {
upgradeDB.createObjectStore('keyval');
});
const idbKeyval = {
async get(key) {
const db = await dbPromise;
return db.transaction('keyval').objectStore('keyval').get(key);
},
async set(key, val) {
const db = await dbPromise;
const tx = db.transaction('keyval', 'readwrite');
tx.objectStore('keyval').put(val, key);
return tx.complete;
},
async delete(key) {
const db = await dbPromise;
const tx = db.transaction('keyval', 'readwrite');
tx.objectStore('keyval').delete(key);
return tx.complete;
},
async clear() {
const db = await dbPromise;
const tx = db.transaction('keyval', 'readwrite');
tx.objectStore('keyval').clear();
return tx.complete;
},
async keys() {
const db = await dbPromise;
return db.transaction('keyval').objectStore('keyval').getAllKeys(key);
},
};
Usage
idbKeyval.set('foo', {hello: 'world'});
idbKeyval.get('foo').then(val => console.log(val));
Set of objects
Imagine we had a set of objects like…
{
"id": 123456,
"data": {"foo": "bar"}
}
Upgrading existing DB
const dbPromise = openDb('keyval-store', 2, upgradeDB => {
switch (upgradeDB.oldVersion) {
case 0:
upgradeDB.createObjectStore('keyval');
case 1:
upgradeDB.createObjectStore('objs', {keyPath: 'id'});
}
});
Adding
dbPromise.then(db => {
const tx = db.transaction('objs', 'readwrite');
tx.objectStore('objs').put({
id: 123456,
data: {foo: "bar"}
});
return tx.complete;
});
Getting all
dbPromise.then(db => {
return db.transaction('objs')
.objectStore('objs').getAll();
}).then(allObjs => console.log(allObjs));
Getting by ID
dbPromise.then(db => {
return db.transaction('objs')
.objectStore('objs').get(123456);
}).then(obj => console.log(obj));
Limitations
Transaction lifetime
An IDB transaction will auto-close if it doesn't have anything to do once microtasks have been processed. As a result, this works fine:
dbPromise.then(async db => {
const tx = db.transaction('keyval', 'readwrite');
const store = tx.objectStore('keyval');
const val = await store.get('counter') || 0;
store.put(val + 1, 'counter');
return tx.complete;
});
But this doesn't:
dbPromise.then(async db => {
const tx = db.transaction('keyval', 'readwrite');
const store = tx.objectStore('keyval');
const val = await store.get('counter') || 0;
const newVal = await fetch('/increment?val=' + val)
store.put(newVal, 'counter');
return tx.complete;
});
Promise issues in older browsers
Some older browsers don't handle promises properly, which causes issues if you do more than one thing in a transaction:
dbPromise.then(async db => {
const tx = db.transaction('keyval', 'readwrite');
const store = tx.objectStore('keyval');
const val = await store.get('counter') || 0;
store.put(val + 1, 'counter');
return tx.complete;
});
All modern browsers have fixed this. Test your browser.
You can work around this in some versions of Firefox by using a promise polyfill that correctly uses microtasks, such as es6-promise.
API
idb
This is your entry point to the API. It's exposed to the global scope unless you're using a module system such as browserify, in which case it's the exported object. If you are using native ES modules, the functions are provided as individual exports, so you can import * as idb from 'idb'
or import { openDb, deleteDb } from 'idb'
.
openDb(name, version, upgradeCallback)
This method returns a promise that resolves to a DB
.
name
and version
behave as they do in indexedDB.open
.
upgradeCallback
is called if version
is greater than the version last opened. It's similar to IDB's onupgradeneeded
. The callback receives an instance of UpgradeDB
.
openDb('keyval-store', 2, upgradeDB => {
switch (upgradeDB.oldVersion) {
case 0:
upgradeDB.createObjectStore('keyval');
case 1:
upgradeDB.createObjectStore('stuff', {keyPath: ''});
}
}).then(db => console.log("DB opened!", db));
deleteDb(name)
Behaves like indexedDB.deleteDatabase
, but returns a promise.
deleteDb('keyval-store').then(() => console.log('done!'));
DB
Properties:
- Same as equivalent properties on an instance of
IDBDatabase
:
name
version
objectStoreNames
Methods:
close
- as idbDatabase.close
transaction
- as idbDatabase.transaction
, but returns a Transaction
UpgradeDB
As DB
, except:
Properties:
transaction
- this is a property rather than a method. It's a Transaction
representing the upgrade transactionoldVersion
- the previous version of the DB seen by the browser, or 0 if it's new
Methods:
createObjectStore
- as idbDatabase.createObjectStore
, but returns an ObjectStore
deleteObjectStore
- as idbDatabase.deleteObjectStore
Transaction
Properties:
complete
- a promise. Resolves when transaction completes, rejects if transaction aborts or errors- Same as equivalent properties on an instance of
IDBTransaction
:
Methods:
abort
- as idbTransaction.abort
objectStore
- as idbTransaction.objectStore
, but returns an ObjectStore
openDb('keyval-store', 1, upgradeDB => {
switch (upgradeDB.oldVersion) {
case 0:
upgradeDB.createObjectStore('keyval');
}
}).then(db => {
const tx = db.transaction('keyval', 'readwrite');
tx.objectStore('keyval').put('hello', 'world');
return tx.complete;
}).then(() => console.log("Done!"));
ObjectStore
Properties:
- Same as equivalent properties on an instance of
IDBObjectStore
:
name
keyPath
indexNames
autoIncrement
Methods:
- Same as equivalent methods on an instance of
IDBObjectStore
, but returns a promise that resolves/rejects based on operation success/failure:
put
add
delete
clear
get
getAll
getAllKeys
count
- Same as equivalent methods on an instance of
IDBObjectStore
, but returns a promise that resolves with a Cursor
:
deleteIndex
- as idbObjectStore.deleteIndex
- Same as equivalent methods on an instance of
IDBObjectStore
, but returns an Index
:
iterateCursor
- see belowiterateKeyCursor
- see below
iterateCursor
& iterateKeyCursor
Due to the microtask issues in some browsers, iterating over a cursor using promises doesn't always work:
const tx = db.transaction('stuff');
tx.objectStore('stuff').openCursor().then(function cursorIterate(cursor) {
if (!cursor) return;
console.log(cursor.value);
return cursor.continue().then(cursorIterate);
});
tx.complete.then(() => console.log('done'));
So in the mean time, iterateCursor
and iterateKeyCursor
map to openCursor
& openKeyCursor
, take identical arguments, plus an additional callback that receives an IDBCursor
, so the above example becomes:
const tx = db.transaction('stuff');
tx.objectStore('stuff').iterateCursor(cursor => {
if (!cursor) return;
console.log(cursor.value);
cursor.continue();
});
tx.complete.then(() => console.log('done'));
The intent is to remove iterateCursor
and iterateKeyCursor
from the library once browsers support promises and microtasks correctly.
Index
Properties:
- Same as equivalent properties on an instance of
IDBIndex
:
name
keyPath
multiEntry
unique
Methods:
- Same as equivalent methods on an instance of
IDBIndex
, but returns a promise that resolves/rejects based on operation success/failure:
get
getKey
getAll
getAllKeys
count
- Same as equivalent methods on an instance of
IDBIndex
, but returns a promise that resolves with a Cursor
:
iterateCursor
- as objectStore.iterateCursor
but over the indexiterateKeyCursor
- as objectStore.iterateKeyCursor
but over the index
Cursor
Properties:
- Same as equivalent properties on an instance of
IDBCursor
:
direction
key
primaryKey
value
Methods:
- Same as equivalent methods on an instance of
IDBCursor
, but returns a promise that resolves/rejects based on operation success/failure:
- Same as equivalent methods on an instance of
IDBCursor
, but returns a promise that resolves with a Cursor
:
advance
continue
continuePrimaryKey