This document provides an overview of Node.js including its key features and common uses. It discusses Node.js' event-driven and non-blocking architecture using the V8 engine and libuv library. Common uses of Node.js include building APIs, rapid experimentation, application modernization, cross-platform experiences, and IoT applications. The document also covers callbacks, NPM, Express, and testing with Mocha.

1. © 2017 Citrix | Confidential
Developing with
Node.js
Tech Bytes
Subramanian Krishnan
Architect, Management & Analytics
AUGUST 3, 2022
© 2017 Citrix | Confidential

2. “People don’t buy
what you do; they
buy why you do it. ”
Simon Sinek
Image source: Google search

3. Stackoverflow survey 2017
Source: https://insights.stackoverflow.com/survey/2017

4. Stackify report 2017
Source: https://stackify.com/trendiest-programming-languages-hottest-sought-programming-languages-2017/

5. 1. Build APIs
• BFF
2. Rapid experimentation
• Hackathons
3. Application modernization
• Strangler
4. Cross platform digital
experiences
• Electron
5. IoT applications
• Small footprint
Forrester Report 2016
Common use-cases

6. • Built almost twice as fast with fewer people
• Written in 33% fewer lines of code
• Constructed with 40% fewer files
PayPal case study
• Double the requests per second vs. the Java
application.
• 35% decrease in the average response time
for the same page.
Source: https://www.paypal-engineering.com/2013/11/22/node-js-at-paypal/

7. What is Node.js?
• Open source
• Cross platform
• Server-side
• Javascript runtime
• Event driven
• Non-blocking IO
• Scaleable

8. Runtime Architecture
• Google V8 => Open-source JavaScript engine,
JIT compiled, efficient GC, fast property access
• Libuv => Multi-platform, high performance,
event driven, async io library
• Event Loop => Single threaded, non-blocking,
executes all user code
• Bindings => Bind JavaScript to native
implementations
• Core Library => System JS libraries for File,
Network, Crypto and other basic functions
Source: https://nodejs.org/en/about/

9. Event-Loop
• Implemented in libuv
• Event-loop starts automatically at program
startup after initialization script is run
• Exits if there are no active callbacks
• Each phase has a FIFO queue of callbacks to
executed
• Network IO performed on single thread
• File IO performed using threads from pool
Event-loop
Source: http://docs.libuv.org/en/v1.x/design.html

10. Thread vs Event-Loop
Source: https://strongloop.com/strongblog/node-js-is-faster-than-java/

11. 1. Most fundamental programming construct of Node.js
2. Introduces a different mental and programming paradigm
3. All async functions needs to have a callback defined
4. By convention callback is usually the last parameter
5. By convention, first parameter of callback is error
Callbacks in Node.js
Source: https://www.tutorialspoint.com/nodejs/nodejs_callbacks_concept.htm

12. • NPM is package manager for JavaScript and Node.js
• World’s largest software registry (477,000)
• Install, share, distribute code and manage
dependencies
• Vibrant ecosystem
• Command line client
• OSS contribution
• 3,052,839,996 weekly package downloads
Node Package Manager (NPM)
Image source: Google search

13. • Minimal and flexible web application framework
• Robust set of features for web and mobile
applications
• Myriad of HTTP utility methods and middleware at
your disposal
• Creating a robust API is quick and easy
• De-facto app server framework for Node.js
• Integrates well with frontend frameworks like
JQuery, AngularJS, ReactJS
Express
Image source: Google search

14. • Feature-rich JavaScript test framework
• Simple and fun
• Test coverage reporting
• Async testing support
• Reports test durations
• before, after, before each, after each hooks
• Optionally run tests that match a regexp
• More…
TDD with Mocha
Image source: Google search

15. • GET /timeofday
 Returns me current
timestamp
Demo – I need an API
• GET /timeofday
 Authenticates request
• GET /timeofday?epoch=true
 Returns me current time as
epoc value
Req1
Req2
Req3

16. Anatomy of the Node.js app