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Biswajit Sundara edited this page Feb 21, 2021 · 7 revisions

Welcome to the JavaScript wiki!

What is Java Script

JavaScript is the light weight and cross platform scripting language for the Web development. This is also used in developing automation scripts and interacting with DOM.

How does it run

Every browser has a JS Engine by default that helps executing the Java Script codes.

  • Internet Explorer has Chakra
  • Firefox has Spider Monkey
  • Chrome has V8

Node.Js

Before we could only run Java script in browsers. Node.Js enables us to run the java script code in our machine. So we can say Node.js is a Runtime environment that executes Java Script outside of a browser. Node.Js is built on top of google chrome's JS engine V8.

Features

  • JS is client side as well as server side language.
  • JS is light weight and interpreted language, means the code runs as it is and we don't have to transform the code before running.
  • JS is dynamically typed. Let's say we have a variable that holds a number, later we can assign it a string.
  • Function as first class object

Installation

  • Install Node.js
  • Install Visual Sudio Code IDE

Execution

To run the java script files use command node filename.js

Comments

  • Single line comments - //this is a comment
  • Multi line comments - /* multi line comment */

Statement Closure

Java script statements will work fine if we or we don't put the semicolon (;) at the end of the statements. However some times it will cause issues so its always a best practice to close each and every statements using semicolon at the end.

ES6

Ecma Script is the organization that standardizes Java Script. On 2015 it released a new version with lot of good features, that is called ES6. Earlier version was ES5. Below are the features in ES6 which were not available in ES5

  • The let keyword
  • The const keyword
  • JavaScript Arrow Functions
  • JavaScript For/of
  • JavaScript Classes
  • JavaScript Promises
  • JavaScript Symbol
  • Default Parameters
  • Function Rest Parameter
  • Map & Set collections
  • Array.find()
  • Array.findIndex()
  • New Number Properties
  • New Number Methods
  • New Global Methods
  • JavaScript Modules

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