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Node, Express, and APIs

What is Node and when should I use it

What is node.js?

Node.js is a JavaScript runtime built on Chrome’s V8 JavaScript engine

an event-based, non-blocking, asynchronous I/O runtime that uses Google’s V8 JavaScript engine and libuv library.

V8 Engine is the open source JavaScript engine that runs in Google chrome and other Chromium-based web browsers

You can test if node.js is installed by typing node -v

npm is the node package manger for node.

npm install -g jshint

^ This will install jshint package globally.

npm init -y

^ Will create and auto-populate a package.json file in the same folder.

The node_modules folder shouldn’t be checked in to version control, and can, in fact, be re-created at any time by running npm install from within the project’s root.

Node.js single threaded & event driven. ` When a new request comes in the server will start processing it. If it then encounters a blocking I/O operation, instead of waiting for this to complete, it will register a callback before continuing to process the next event`

Downsides

• Intensive operations could potentially crash
• Developers dislike callback based style of coding that js imposes

Hello World

const http = require('http');

http.createServer((request, response) => {
  response.writeHead(200);
  response.end('Hello, World!');
}).listen(3000);

console.log('Server running on http://localhost:3000');

Node.js is suited for building applications that require some form of real-time interaction or collaboration. (i.e. chat sites, or apps such as CodeShare, building APIs, Data Streaming.)

Express.js

Express.js is a Node.js web framework that has gained immense popularity due to its simplicity. It has easy-to-use routing and simple support for view engines, putting it far ahead of the basic Node HTTP server.

Express does this out of the box

name	definition
routing	This is how /home /blog and /about all give you different pages. Express makes it easy for you to modularize this code by allowing you to put different routes in different files.
Middleware	If you’re new to the term, basically middleware is “software glue”. It accesses requests before your routes get them, allowing them to handle hard-to-do stuff like cookie parsing, file uploads, errors, and more.
views	Views are how HTML pages are rendered with custom content. You pass in the data you want to be rendered and Express will render it with your given view engine.

Express Application structure

name	definition
Routes	Where you’ll put your router files. The generator creates two files, index.js and users.js, which serve as examples of how to separate out your application’s route configuration.
Views	The views folder is where you have the files used by your templating engine. The generator will configure Express to look in here for a matching view when you call the render method.
App.js	It sets up your Express application and glues all of the different parts together. Let’s walk through what it does.

server.js needs 3 parts

// new route
app.get(route, function)

// function that runs fromt the route
function doStuff(req, res){
  res.json(foo) // returns json file
  res.send(text) // sends text
}

// constructor so you know what to return from the server
function Construct(obj, data){ 
  this.potato = obj
  this.carrot = data.whatIWant
}

// turns on server listens
app.listen(PORT, () =>{
  console.log(`Listening on ${PORT}`)
})