1. Node.js Express Web Applications
Microsoft Virtual Academy
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Mastering Node.js, Part 6
Node.js Express Web Applications
Eric W. Greene
Produced by

2. Course Overview Getting Started with Express Working with Static Files
Configuring Routes
Extracting Data from the URL
Working with a Request Body
Working with Cookies
Authentication with Passport

3. Getting Started with Express
The course assumes some basic knowledge of Node.js and the JavaScript programming language
To run the examples on your machine, you will need Node.js installed
Node.js can be downloaded from here:
Install version 6 or later
If you do not understand the basics of these technologies, then watch the WintellectNOW courses, Introduction to Node.js, Node.js Modules & Node.js Packages

4. Getting Started with Express
Express is a Web Framework used to configure Node's HTTP module
Fast
Un-opinionated
Minimalist
Express is distributed via an NPM package
Express should be installed locally to each project, not globally
To install: npm install express

5. Getting Started with Express

6. Getting Started with Express
Provides support for routing and serving static files
Almost all other functionality is provided through third-party middleware modules
Processing request body – Body Parser
Working with cookies – Cookie Parser
Using session – Express Sessions
Handling Authentication - Passport

7. Creating a Hello World Express Application

8. Working with Static Files
Serving up static files is provide directly by Express itself
To serve up static files, the express.static function is invoked with the folder path to the files to be served

9. Working with Static Files
Static file handling supports several options which can be passed as a second argument to the static function call, here are two of those options
index – specifies the file name of the default file to serve from a folder if no file is specified, default value is 'index.html'
setHeaders – allows a function to be set for specifying custom headers on static file requests

10. Serving Up Static Files

11. Routing Requests
Requests can be routed based upon the following factors
HTTP Method – GET, POST, PUT, DELETE and many more
URL Path – Path of the request URL can be matched against patterns
Routes are match based upon the order they are registered
Each match is handled by a function which is passed a request and a response object allowing the handler to access information from the request and contribute to the generation of the response
Each handler can pass the request along via the next function

12. Routing Requests Matches all HTTP verbs Matches the GET verbs
Functions for POST, PUT, DELETE as well as app.METHOD are also available

13. Routing Requests

14. Extracting Data from the URL
Two kinds of data are available in the URL
URL Parameters – exposed as params property of the request object
Query String Parameters – exposed as the query property on the request object
URL Parts
:8080 /person/2 ?detailed=true #home |
Protocol
Domain Name / IP Address
Port
Path
Query String
Client-Side

15. Working with URL Parameters and Query String Values

16. Working with a Request Body
Express does not support processing of the request body
Instead, middleware can be used to process the request body
Body Parser – used to process URL encoded and JSON content
Multer (and many others) – used to process file uploads
The request body is a Node.js stream, and the stream data can be read and processed manually

17. Working with a Request Body
Body Parser determines whether to process the request body as URL encoded of JSON data based upon the request Content-Type
Body Parser makes the data available through the body property on the request object
Body Parser should be loaded before any routes which need access to the request body data

18. Extracting URL Encoded and JSON Data from the Request Body

19. Working with Cookies
Express provides the ability to write cookies to the response, but middleware is needed to parse cookies in the request
The most common middleware is named Cookie Parser
It is installed using: npm install cookie-parser
The cookie parser middleware must be loaded before any routes which need access to cookies
The response cookie function writes a cookie to the response by using the Set-Cookie header

20. Enabling Cookies with Middleware

21. Authentication with Passport
Authentication for Express is commonly provided by Passport
Passport provides many different strategies for authenticating users
User accounts stored in local databases
Facebook, Twitter, Google
OAuth and OAuth2 Providers
WS Federation and SAML2

22. Authentication with Passport
Passport relies express-session middleware to use session-based cookies to track logged in users
Sessions are not required if credentials like an API-key are provided on every request
Passport is well suited for user applications as well as REST services

23. Authentication with Passport

24. Passport Authentication with Session Cookies

25. Conclusion Express is a Node.js web framework
It makes configuring the Http Server a lot easier
Provides routing and static file delivery out of the box
Relies upon third-party middleware to process the request body, cookies, sessions, authentication, etc…
Popular, easy to use, and very flexible