My study notes for the course, built from lecture notes, readings, and the code we write in class.
SI 679 builds backend web services in TypeScript with Node.js and Express. It starts with a bare HTTP server, then adds routing and middleware, automated tests with Vitest and supertest, a MongoDB database, a layered REST API structure (routes → controllers → services → repositories), and unit tests with mocks and spies.
| Page | Topic | Main code |
|---|---|---|
| Page 0: JS & TS Foundations | JavaScript refresher, TypeScript types, type vs interface | practice/, TS basics exercise |
| Week 1: Servers & Express Intro | Client–server model, web servers, first Express app | Week 1 in-class server.js |
| Week 2: Routing, Middleware & Testing | Express routing & middleware, unit testing | Books router, HW1 SliceDrop |
| Week 3: MongoDB & Testing with a Database | MongoDB integration, testing with Vitest | Products + MongoDB driver |
| Week 4: REST APIs & Layered Architecture | REST API design, project structure in layers | REST layers starter |
| Week 5: Testing (E2E, Unit, Mocks & Spies) | Repositories & business logic, custom errors, e2e and unit tests with vi.fn / vi.spyOn | /products testing starter |
mongod is the MongoDB server program. It has to be running before your code (or Compass or mongosh) can connect to the database at mongodb://127.0.0.1:27017. Start it in its own terminal and leave that terminal open:
mongod --dbpath ~/data/mdata--dbpath tells mongod which folder holds the database files. Stop the server with Ctrl+C. To poke at the data from another terminal, run mongosh, then use week3db, then db.products.find(). More in Week 3.
Writing code? The Cheat Sheet collects every pattern on one page: routes, req/res, status codes, middleware, MongoDB CRUD, the layer template, and test setup.
How to use this notebook
Read the Overview and Key concepts first, then open the Code walkthrough next to the linked source file. Try the Review questions before opening the answers.