idb-kv-store

idb-kv-store

Persistent key-value store for web browsers backed by IndexDB

idb-kv-store uses asynchronous get/set operations to persist everything in IndexDB. Sometimes IndexDB is needed over something like localStorage due to storage size constraints or simply, localStorage is not available within web workers. Since IndexDB presents a complex api, storing simple key-value pairs can be complicated which this project greatly simplifies. Since everything is persisted to IndexDB, the data you store is available across multiple web sessions and within web workers.

This module can be used with browserify or the idbkvstore.min.js script can be included which will attach IdbKvStore to window.

Usage

var store = new IdbKvStore('your stores name')

// Store the value 'def' at key 'abc'
store.set('abc', 'def', function (err) {
  store.get('abc', function (err, value) {
    console.log('key=abc  value=' + value)
  })
})

Promises are also supported!

var store = new IdbKvStore('your stores name')

// Store the value 'def' at key 'abc'
store.set('abc', 'def')
.then(() => store.get('abc'))
.then((value) => console.log('key=abc  value=' + value))

API

store = new Store(name, [opts])

Instantiates a new key-value store. name is the name of the database used to persist the data. So multiple Store instances with the same name will be sharing the same data.

opts can take the following options:

• opts.onready - A zero argument function to call when the IndexDB database is open
• opts.onerror - This function is called when IndexDB experiences an error. It accepts one error argument. If this is undefined, the error is thrown instead.

store.set(key, value, [cb])

Stores the value at key; the value can be retrieved through store.get(key). When the store operation completes, cb is called with cb(err). err is null if the store was successful. If cb is undefined then a promise is returned instead. If the key already exists then the old value is replaced with the new one.

store.add(key, value, [cb])

The same as store.set(...) except if the key already exists, an error is returned in the callback.

store.get(key, [cb])

Retrieves the value at key. When the value is retrieved, cb is called with cb(err, value). If the retrieval was successful then err will be null. If cb is undefined then a promise is returned instead. If the key does not exist then undefined is returned as the value; no error is raised.

store.remove(key, [cb])

Removes the given key from the store and calls cb(err) upon completion. err is null if the removal was successful. If the key did not exist before the removal, the removal is still considered successful. If cb is undefined then a promise is returned.

store.clear([cb])

Removes all entries from the store, and calls cb(err) upon completion. err is null the clear was successful. If cb is undefined then a promise is returned.

store.keys([cb])

Retrieves the list of keys stored. When the list is retrieved, cb is called with cb(err, keys). If cb is undefined then a promise is returned.

store.json([cb])

Retrieves the entire key-value store as a json object. When the json representation has been retrieved, cb is called with cb(err, json). If cb is undefined, then a promise is returned.

store.count([cb])

Retrieves the number of entries in the store, and calls cb(err, count) upon retrieval. err is null if the count was successful, in which case count will hold the value. If cb is undefined, then a promise is returned.

License

MIT. Copyright (c) Austin Middleton.