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Recitation 2: Node.js


This recitation aims to highlight the basics of Node.js by walking students through the implementation of a basic To-Do app.

Staff Overview

Full-stack Development

Different levels of the stack: - Backend - Frontend - Database - Deployment - Testing and more


What is Node?

  • Back-end JavaScript runtime environment, runs on the V8 JavaScript Engine
  • Used for server-side scripting
  • Has an event-driven architecture capable of asynchronous(non-blocking) I/O.
  • Used to build fast, powerful and scalable web applications

Asynchronous or Non-blocking I/O

Every request consists of:

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  • Non-blocking I/O allows a thread to suspend a request while it’s performing I/O to go work on a different request
  • Runs on a single-thread event loop, using non-blocking I/O calls, allowing it to support tens of thousands of concurrent connections without incurring the cost of thread context switching
  • Concurrency (in Node) refers to the Event Loop’s capacity to execute Javascript “callback” functions after completing other work

Node js async options

  • Callbacks: Functions passed to another functions
  • Promises (and promise chains): Structured callbacks
  • Generators: Functions which can be exited/paused and later re-entered
  • Async/Await: Combining generators and promises

Node Package Manager (npm)

Consists of: - npm client - command line tool - npm registry - an online database of public and paid-for private packages

The largest ecosystem of open-source libraries in the world

Model View Controller (MVC)

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Model View Viewmodel (MVVM)

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  1. mkdir into your project folder (todo-app) and cd into it
  2. npm init
  3. npm i --save-dev typescript @types/node @types/express npm i cors dotenv mongoose
  4. Create tsconfig.json file
  5. Write code, as seen in either the MongoDB or Postgres reference solution
  6. npm start (to start the server)
  7. (optional) Play with the server, send it post requests

Steps for building off of references

  1. Clone either the MongoDB or Postgres reference solution
  2. cd into server directory with cd server
  3. Run npm install in command line
  4. Run npm start in command line
  5. (optional) Play with the server, send it post requests


  • Download Postman to test your server/API
  • Homework 2 due Thursday
  • Meet with your group soon if you haven’t already!