'use strict';

// Interface definition

class Transaction {

constructor() {

// this.delta

}

static start(data) {

// place implementation here

const obj = {};

return [obj, this];

}

commit() {}

rollback() {}

revoke() {}

timeout(msec) {}

before(event, listener) {}

after(event, listener) {}

// Events: commit, rollback, revoke, set, get, timeout

}

module.export = { Transaction };

// Usage

const data = { name: 'Marcus Aurelius', born: 121 };

const [obj, transaction] = Transaction.start(data);

console.dir({ data });

obj.name = 'Mao Zedong';

obj.born = 1893;

obj.city = 'Shaoshan';

obj.age =

new Date().getFullYear() -

new Date(transaction.born.toString()).getFullYear();

console.dir({ obj });

console.dir({ delta: transaction.delta });

transaction.commit();

console.dir({ data });

console.dir({ obj });

console.dir({ delta: transaction.delta });

obj.born = 1976;

console.dir({ obj });

console.dir({ delta: transaction.delta });

transaction.rollback();

console.dir({ data });

console.dir({ obj });

console.dir({ delta: transaction.delta });