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09-nodejs

README.md

Node.js and Express

Goal

  • Understand how to install and use Node and Express, to create a Node applications
  • Creating Node and Express based servers
  • RESTful Routing with Express
  • Understand and use middleware for Node applications

Node

What is Node.js

  • Node.js allows to take javaScript out of the browser and allows it to interact directly with the hardware of a computer to create desktop applications.

The Node REPL (Read Evaluation Print Loops)

  • By installing node, we also installed the node REPL and to access it we just need to write the command node inside the terminal.
  • > bracket means you are already insde the REPL, and you write any javaScript syntax inside it.
  • To exit repl, type exit or hit Ctrl C twice.

How to Use the Native Node Modules

  • In order to use the node modules, we need to require it first.
  • const or constant cannot be overwrite, you cannot change it once you declared it.
  • Things that you can do using file system modules, is specify paths, open files, change files, access, read, and write to the local file system.

Create a file file1.txt and then copy and sync file1.txt to file2.txt:

const fs = require('fs');

// fs.copyFileSync(src, dest[,flags]);
fs.copyFileSync('file1.txt', 'file2.txt');

The NPM Package Manager and Installing External Node Modules

  • NPM (Node Package Manager) is bundled with node.
  • packages on NPM are bits of reusable code that somebody else wrote and using NPM you can incorporate those packages into your own projects. Saving you the time and effort that's required to write those bits of code yourself.

Express

  • Express is a node framework, just like jQuery to JavaScript, Express is to Node.

    • a bunch of code that somebody else wrote that add extra features and helps to organize and structure your code specifically for web applications built with node.

  • Can do atom . or code . inside terminal to open the current directory to atom/code.

  • install express and --save means save it in the dependencies list

    $ npm install express --save

  • req or request object represents the HTTP request and has properties for the request query string, parameters, body, HTTP headers, and so on.

    app.get('/', function (req, res) { })

  • res or response object represents the HTTP response that an Express app sends when it gets an HTTP request.

    res.send('Hello World')

  • nodemon will monitor any change in your source and automatically restart your server. -g means globally, not just on your current project.

    $ npm install -g nodemon
$ nodemon server.js

  • __dirname will give you the file path of the current file.

  • body-parser module extract the entire body portion of an incoming request stream and exposes it on req.body.

    • parses the JSON, buffer, string and URL encoded data submitted using HTTP POST request.
    $ npm install body-parser
    const bodyParser = require('body-parser');

  • use urlencoded to pass data that comes from an html form.

  • extended: true allows us to post nested objects.

    app.use(bodyParser.urlencoded({extended: true}));

Resources