• Node.js is a javascript runtime built on Chrome's V8 javascript engine. it uses an event-driven , non-blocking I/O model that makes it lightweight and efficient. (from
  • allows us to write javascript code on the server side/backend

Interact with Node Console

  • has its own version of the console --- on command line
  • not that useful
  • it's a REPL
  • ctrl-C ctrl-C to quit
  • can't use some commands you can use in the javascript console can't be used here (DOM commands , alert(), etc) because they are browser/frontend based

Run a File with Node

  • create a js file and execute it on the command line with node fileName.js
    • can print console.log() outputs in the terminal
  • to run more complicated things that are running on servers and such use node app.js command
    • it will tell you it is running on port 3000, which is where you can view the app in the browser


  • nodes javascript package manager
  • can't include packages with script tags like with libraries because the server side doesn't use html
  • an alternative is yarn -- another package manager that was created by Facebook
    • can use either package manager, but make sure to stick with the same one for a whole project

Installing packages and Using Packages

  • npm install or yarn install to install a package
  • install in project root
  • in your .js file use format: let variableName = require('packageName');
  • then you will call methods with variableName.methodFromPackage();

Package.json and NPM Init


  • All npm packages contain a file, usually in the project root, called package.json - this file holds various metadata relevant to the project. This file is used to give information to npm that allows it to identify the project as well as handle the project's dependencies. It can also contain other metadata such as project description, the version of the project in a particular distribution, license information, even configuration data - all of which can be vital to both npm and to the end users of the package. The package.json file is normally located at the root directory of a Node.js project. --- this description was from docs, which doesn't exist anymore
  • json stands for javascript object notation
  • contains a list od all the dependencies needed to run the app, but doesn't download them automatically
    • json dependencies analogy paraphrased from Colt Steele: Suppose you have a great recipe and you want your friend in Denmark to be able to replicate it. One option would be to buy all the ingredients, measure them, package them in bags, and then put in a box with instructions and ship it to the friend. Alternately, you can send them instructions with a description of all the ingredients and their quantities and send that. Then friend can just prepare it on their own. The package.json is like the mailed recipe. It will list all the dependencies and then the user can go and install those packages themselves.

npm init

  • used to create a package.json file inside the directory where the application will exist
  • it will ask questions and use the provided data to make the package.json file for us at the end
    • it will put its guesses at the answers in parenthesis --- if that is what you want you can just hit enter
    • won't have any dependencies yet
  • to add dependencies install a package with the --save flag
    • flag automatically saves the package name and version to the package.json dependencies list
  • npm init -y - automatically fills in package.json with what it thinks should be there

Automate the Restarting of the Node Server

  • keeps you from having to stop and restart your Node server manually everytime you edit your code
  • use Nodemon
  • not a package that is installed to your project
  • run npm i -g nodemon to install
  • global install allows us to use anywhere on our computer with any project
  • run nodemon command in node console to use --- it will run in the background and restart the server automatically

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