Skip to main content

Introduction To JavaScript

JavaScript Language has following characteristics:
  • Lightweight: Small memory footprint, easy to implement
  • Interpreted: No compilation, Instructions executed only
  • Object Oriented: Modeled around objects
  • First-class functions: Functions used as variables and parameters
  • Scripting language: Writing instructions for runtime environment
JavaScript is used for 
  • Client side web development
    • Frameworks: JQuery, AngularJs, React, EServer-side
  • Server-side web development
    • Frameworks: NodeJS, Express
Variable declaration and definition
  • Declaration: Give a name to a variable
  • Definition: Assign a value to the variable
Equal operations 
  • =: assigning value to a variable (a=30)
  • ==: check the values (doesn't consider types)
  • ===: check the values and types
Functions: 
  • no overloading
  • functions are objects
  • functional expression : assign function to variable
  • anonymous function: function with no name
Array methods
  • push(value): value is appended to the last position of an array
  • pop(): last element is removed
  • shift():first element is removed
  • unshift(value): values is appended as first element

Other Points 

  • Native JavaScript: Doesn't use any framework 
  • Doesn't associate type with variables
  • If you declare a variable and not define yet: it has undefined value
  • type of null in Javascript: object
  • For all non-zero values variable return as true.
  • JavaScript is not a class-based language: can add properties to object dynamically
  • Arrays behave like an object
  • Arguments: keyword that gets function arguments as list






Comments

Post a Comment

Popular posts from this blog

Hibernate

Hibernate is an ORM (Object Relational Mapping) tool which is primarily used in the data layer. Object Relational Mappings Problems There are several problems can occur when you are trying to save objects in the database from the scratch without using Hibernate. Mapping member variables to columns Mapping relationships Handling data types Managing changes to an object Set Up the Development Environment  Following steps are briefly pointed out how to set up Hibernate on your local machine. Download the hibernate jar files Create a project in Eclipse Right click on the project name and go to properties Navigate to libraries tab Add library and import jar files (lib-> JPA/required) Add Postgres JDBC driver as jar file Configurations After you set up the Hibernate you have to create hiberante.cfg.xml file and do some configurations like setup database details, entity class, etc. Dialect: Define what kind of language should use to talk...
Post a Comment
Read more

Model-View-Controller (MVC)

MVC(Model-View-Controller) is a software design pattern.It divided your applications into three components Model: Contain business rules and application Data View: Presentation layer (user interface) Controller: Handles the communication between view and model  Objectives of MVC Promote code usability Implement separation of concerns  Separate user interface and software logic Web Frameworks That Use MVC There are several web frameworks that use MVC design pattern.  Ruby On Rails (Ruby) Angular (JS) Django (Python) Express (JS) Flask (Python) Codeigniter (PHP) Simple UseCase for MVC In this use case scenario, Browser sends information that needs to create Employee Object, and Controller save that information in Model and Update the Employee View. Following Image shows the class diagram for above Scenario. Implementation:  https://github.com/kaosadi17/MVC
Post a Comment
Read more