local database with javascript

1Your best option is:
2https://pouchdb.com/

1//get in GitHub
2//more info in https://pouchdb.com
3var db = new PouchDB('dbname');
4
5db.put({
6  _id: 'dave@gmail.com',
7  name: 'David',
8  age: 69
9});
10
11db.changes().on('change', function() {
12  console.log('Ch-Ch-Changes');
13});
14
15db.replicate.to('http://example.com/mydb');