JavaScripters Event Sep 17, 2016 · 2:00 PM: Scalable Javascript Design Patterns

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JavaScripters www.javascripters.org
JavaScripters
Community to Connect, Share & Explore
http://www.javascripters.org
Email: pune.javascripters@gmail.com

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JavaScripters www.javascripters.orgwww.javascripters.org
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About JavaScripters
JavaScripters is an initiative taken for front-end engineers community to share and gain JavaScript
basic and advance knowledge along with moto to connect all javascripters together.
We conduct technical discussion forums, sessions, workshops, trainings and knowledge sharing
meet-ups around the city, for all front-end / UI engineers on core & advance(object oriented) level
javascript concepts, along with all latest javascript frameworks like AngularJS, NodeJs, emberJs,
TypeScript, ReactJs technologies by experts.
• Since : April 2015
• Members : Around 2500+
• Speakers & Mentors : 17
• Events/ Meetup Conducted: 5
• Feature Planned Events : 10 events confirmed till December 2016
Our initiatives:
WhatsApp Group (2)
Meetup Groups
JavaScriptes
PuneJs
HTML5-Web-Mobile-Development-Meetup
Pune-UX-UI-Engineers
WebF

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List of upcoming events
3
1.JS Performance tips and tricks
2.BootStrap , CSS and Responsive Design
3.JavaScript Design Patterns
4.Introduction of Design thinking for front-end Engineers
5.React JS with Material design
6.Introduction to Angular 2.x
7.Practice with TypeSpcript
8.Introduction to ES6
9.Automated javascript workflow with Gulp
10.NodeJs practice session

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Our Sponsor

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• Laxman M
• Tushar Jadhav
About Speaker

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WHY ARE WE HERE
?

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What is Pattern?
A pattern is a reusable solution that can be applied to commonly occurring
problems.
Another way of looking at pattern is as templates for how we solve problems.

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Anti-Patterns
Anti-patterns represents a lesson that has been learned.
• Describes a bad solution to a particular problem that resulted in bad situation
occurring
• Describe how to get out of said situation and how to go from there to a good
solution

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Benefits
• Patterns are proven solutions
• Patterns can be easily reused
• Patterns can be expressive

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What is “good” pattern?
A pattern is considered good if it
• solves a particular problem
• does not have an obvious solution
• describes a proven concept
• describes a relationship

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Categories of Design Patterns
• Creational Design Patterns
focus on object-creation mechanism
• Structural Design Patterns
concerned with object composition and relationship between objects
• Behavioural Design Patterns
focus on improving or streamlining the communication between disparate
objects

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Overview
• Constructor Pattern
• Module Pattern
• Singleton Pattern
• Observer Pattern
• Prototype Pattern
• Facade Pattern
• Factory Pattern
• Decorator Pattern

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Constructor Pattern
A constructor is a special method used to initialise a newly created object once
memory has been allocated for it.

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Module Pattern
Modules are an integral piece of any robust application’s architecture and
typically help in keeping the units of code for a project both cleanly separated
and organised.
Modules can be implemented using
• Object literal notation
• The Module pattern
• AMD modules
• CommonJS modules
• ECMAScript Harmony modules

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The Module pattern
A way to provide both private and public encapsulation for classes.

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The Module pattern
Advantages:
• Encapsulation
• Privacy
Disadvantages:
• Cannot access private members in the methods that are added to the object
at later point
• Inability to create automated unit tests for private members

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Revealing Module Pattern
In Module pattern,
1. repeat the name of module each time when accessing public method/variable
from other public method
2. switch to object literal notation to make things public
The updated module pattern in which all the functions and variables are defined
in private scope and return an anonymous object with pointers to the private
members to reveal them publicly.

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Revealing Module Pattern
Advantages:
• Readability
Disadvantages:
• If a private function refers to public function, that public function can’t be
overridden
• Public object members that refer to private variables are also subject to no-
patch rule

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Singleton Pattern
The singleton pattern restricts instantiation of a class to a single object.
Classically, the Singleton pattern can be implemented by creating a class with a
method that creates a new instance of the class if one doesn’t exist.
In JavaScript, Singletons serve as a shared resource namespace which isolate
implementation code from the global namespace so as to provide a single point
of access for functions.

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Observer Pattern
In Observer pattern, an object(subject) maintains a list of objects depending on
it(observers) automatically notifying them of any changes to state.

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Difference between Observer and Pub/Sub Pattern

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Observer and Pub/Sub Pattern
Advantages:
• Loosely Coupled
• Flexibility
Disadvantages:
• In Pub/Sub, by decoupling publishers from subscribers, it can sometimes
become difficult to obtain guarantees that particular parts of the application
are functioning as we may expect

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Prototype Pattern
Creates objects based on a template of an existing object through cloning.

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Facade Pattern
This pattern provides a convenient higher-level interface to a larger body of
code, hiding its true underlying complexity.

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Facade Pattern
Advantages:
• Simplicity
• Abstraction
Disadvantages:
• Performance

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Factory Pattern
A factory provides a generic interface for creating objects, where we can
specify the type of factory object we wish to create.

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Decorator Pattern
Decorators are structural design pattern that aims to promote code reuse. They
can be used to modify existing systems where we wish to add additional
features to objects without the need to heavily modify the underlying code.

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Decorator Pattern
Advantages:
• Flexible
Disadvantages:
• If poorly managed, it can add complexity

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Can we check what
we have learned ?

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Register for upcoming events
31
3.BootStrap , CSS and Responsive Design
4.Introduction of Design thinking for front-end Engineers
5.React JS with Material design
6.Introduction to Angular 2.x
7.Practice with TypeScript
8.Introduction to ES6
9.Automated javascript workflow with Gulp
10.NodeJs practice session
11. Total (3) online webinar under planning

JavaScripters Event Sep 17, 2016 · 2:00 PM: Scalable Javascript Design Patterns

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