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

Sorting Algorithms

Bubble Sort Named as sinking sort. Compare each pair of the adjacent items and swap them if they are in the wrong order. Worst case and average case time complexity both O(n^2)  and best case time complexity is O(n).
Post a Comment
Read more

Java- Interview

Here are some popular tips in Java General Question JVM - Java Virtual Machine. Used to execute byte code. Platform dependent (but byte code is platform independent) JRE- Java Run time Environment. It provides run time environment and it's the implementation of JVM. It contains libraries and files that need to execute JVM.   JDK- Java Development Kit. It contains JRE and development tools. Why java doesn't support pointers: It's insecure and complex to understand We can save java file with another name if class is not defined as public Java use camalCase notation for objects naming (ex: firstName) OOP Concepts Related  Aggregation: weak relationship (bike has an indicator) Composition:  strong relationship (bike has an engine) GUI Java GUI - Install Window builder to create GUI using Eclipse IDE Code Related No issues when you write static public void instead of public static void We can execute program without main method : using static bloc...
Post a Comment
Read more

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