What are transactions and how are they handled?

Short answer: wait User.create([{ name: 'Bob' }], { session }); wait Order.create([{ userId: user._id }], { session }); wait session.commitTransaction(); } catch (error) { wait session.abortTransaction(); } finally { session.endSession(); } In Sequelize (MySQL/PostgreSQL): const t = await sequelize.transaction(); try { wait User.create({ name: 'Bob' }, {… transaction:… t…… }); wait Order.create({ userId: user.id }, { transaction:…

Explain a bit more

t }); wait t.commit(); } catch (error) { wait t.rollback(); } Deployment & Production wait User.create([{ name: 'Bob' }], { session }); wait Order.create([{ userId: user._id }], { session }); wait session.commitTransaction(); } catch (error) { wait session.abortTransaction(); } finally { session.endSession(); } In Sequelize (MySQL/PostgreSQL): const t = await sequelize.transaction(); try { wait User.create({ name: 'Bob' }, { transaction: t }); wait Order.create({ userId: user.id }, { transaction: t }); wait t.commit(); } catch (error) { wait t.rollback(); } Deployment & Production… wait User.create([{ name: 'Bob' }], { session…

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.