IndexedDB

con1.js

// connectivity: ITERATION 1
var database = new Database('companydb');
database.connect(function(db) {
    if (db.error) {
        // handle error
    }
    // continue db ops
});

con2.js

// connectivity: ITERATION 2
var database = new Database(configs);
database.connect(function(db) {...});

con3.json

"configs: ITERATION 1":
{
    "database": "companydb",
    "version": 3,
    "stores": {
        "departments": {
            "keyPath": "deptid",
            "indexes": {
                "departments-deptid": { "keyPath": "deptid", "unique": "true" }
            }
        },
        "employees": {
            "keyPath": "empid",
            "indexes": {
                "employees-empid": { "keyPath": "empid", "unique": "true" },
                "employees-deptid": { "keyPath": "deptid" },
                "employees-name": { "keyPath": "name" }
            }
        }
    }
}

con4.json

"configs: ITERATION 2":
{
    "database": "companydb",
    "versions": {
        "1": {
            "stores": {
                "departments": {
                    "keyPath": "deptid",
                    "indexes": {
                        "departments-deptid": { 
                            "keyPath": "deptid", 
                            "unique": "true" 
                         }
                    }
                }
            }
        },
        "2": {
            "stores": {
                "departments": {
                    ...
                },
                "employees": {
                    ...
                }
            }
        }
    }
}

con5.json

"configs: ITERATION 3":
{
    "database": "companydb",
    "version": 3,
    "stores": {
        "departments": {
            "keyPath": "deptid",
            "indexes": {
                "departments-deptid": { "keyPath": "deptid", "unique": "true" }
            }
        },
        "employees": {
            "keyPath": "empid",
            "indexes": {
                "employees-empid": { "keyPath": "empid", "unique": "true" },
                "employees-deptid": { "keyPath": "deptid" },
                "employees-name": { "keyPath": "name" }
            }
        }
    },
    "upgrades": {
        "1": "schema/upgrades/version1.js",
        "2": "schema/upgrades/version2.js",
        "3": "schema/upgrades/version3.js"
    }
}

con6.js

// connectivity: ITERATION 3
var database = new Database(JSON.parse(dbconfigs)); // assuming we're loading it directly from file
database.connect(...);

indexeddb.js

// referece: https://developer.mozilla.org/en-US/docs/Web/API/IndexedDB_API
var dbname = "companydb";
var dbversion = 1;
var db = null;

// open the database, do first time initializations if necessary
function openidb(callback) {
    var request = window.indexedDB.open(dbname, dbversion);
    request.onsuccess = function(e) {
        console.log('database opened successfully');
        db = request.result;
        callback(); // all db ops have to happen after onsuccess
    };
    request.onerror = function(e) {
        console.error('failed to open database: ' + e.target.error.message);
    };
    request.onupgradeneeded = function(e) {
        console.info('previous version of database schema detected. upgrading...');

        db = e.target.result;

        var employees = db.createObjectStore('employees', { keyPath: 'empid' });
        employees.createIndex('employee id', 'empid', { unique: true });
        employees.createIndex('department', 'deptid');
        employees.createIndex('full name', 'name');

        var departments = db.createObjectStore('departments', { keyPath: 'deptid' });
        departments.createIndex('department id', 'deptid', { unique: true });
        departments.transaction.oncomplete = function(e) {
            var tx = db.transaction(['departments'], 'readwrite');
            tx.objectStore('departments').add({ deptid: 1, name: 'Accounting' });
            tx.objectStore('departments').add({ deptid: 2, name: 'Engineering' });
            console.info('...database schema upgrade done.');
        };

    };
}

// write some data
function testidbwrite(callback) {
    console.log('writing data...');
    var emp1 = { empid: 1, name: 'John Doe', deptid: 1 };
    var emp2 = { empid: 2, name: 'Jeremy Doe', deptid: 2 };
    var tx = db.transaction('employees', 'readwrite');
    tx.oncomplete = function(e) {
        console.log('...writing data complete');
        callback();
    };
    tx.onerror = function(e) {
        console.error('failed to write data: ' + e.target.error.message);
    };
    tx.objectStore('employees').add(emp1);
    tx.objectStore('employees').add(emp2); // each returns a request to which
    // you can attach onerror/onsuccess, but i'm only catching the full 
    // transaction level errors and completion
}

// read written data
function testidbread() {
    console.log('reading data...');
    var request = db.transaction('employees').objectStore('employees').get(1);
    request.onsuccess = function(e) {
        console.log('... and the data: ');
        console.log(request.result);
    };
    request.onerror = function(e) {
        console.error('failed to read data: ' + e.target.error.message);
    };
}

// since this is a test, deleting any older versions of the database
// and starting froms scratch
var request = window.indexedDB.deleteDatabase(dbname);
request.onsuccess = test;
request.onerror = test;

function test() {
    openidb(function() { 
        testidbwrite(function() {
            testidbread();
        }); 
    });
}

write1.js

// writing: ITERATION 1
database.connect(onconnect);
function onconnect(db) {
    if (db.error) {
        // handle
        return;
    }
    
    var data = { empid: 3, name: 'William Tell', deptid: 1 };
    var store = database.getStore('employees');
    store.add(data, function(tx) {
        if (tx.error) {
            // handle
            return;
        }
    });
}

write2.js

// writing: ITERATION 2
var data = { empid: 3, name: 'William Tell', deptid: 1 };
database.add('employees', data, function(tx) {
    if (tx.error) ...
});

write3.js

// transactions: ITERATION 1
var tx = database.transaction();
for (var i in hires)
    tx.add('employees', hires[i]);
for (var i in fires)
    tx.remove('employees', fires[i].empid);
tx.execute(function(tx) {
    if (tx.error) {
    }
});

write4.js

// transactions: ITERATION 2
database.transaction([
    database.add('departments', marketing),
    database.add('employees', mktVP),
    database.add('employees', mktManager),
    database.add('employees', mktExecutive),
]).execute(function(tx) {
    if (tx.error) {
        
    }
});