Introduction to Javascript

Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript was designed to specify the behaviour of the web pages.

Key Features

  • Open-source
  • Just-in-time compiled language
  • Embedded along with HTML and makes web pages alive
  • Originally names as LiveScript.
  • Executable in both browser and server which has Javascript engines like V8(chrome), SpiderMonkey(Firefox) etc.
  • Many giant companies like Microsoft, Paypal, Netflix, Uber, Google, Facebook, LinkedIn etc use Javascript.

This tutorial is for beginners to understand the modern javascript concepts.

Why you should learn Javascript?

  • Javascript is one of the very popular language and you can develop both front-end and back-end applications using different frameworks of Javascript like node.js, react, angular etc.
  • You can create scalable applications without any environment setup as it is available on all modern browsers.
  • You can create mobile-applications too
  • Developer friendly as you can find tons of existing frameworks and libraries which can be directly used in your application.
  • Easy to learn language.

Why Javascript is popular?

One can't deny that Javascript is everywhere. Below key qualities of modern Javascript made it so popular.

  • It integrates fully with HTML/CSS.
  • Supported by almost all browsers.
  • Easy and simple and scalable.
  • Tons of frameworks and great community support and especially it's an open-source language.

Javascript Basics

Sample HelloWorld program

console.log("Hello, World!"); // prints Hello, World!

console.log is used to print the message to get displayed to the user.

Statements and Semicolons

  • The above line of code is called a statement.
  • Statements are seperated by semi-colon(;)
  • Javascript doesn't throw error in absence of semi-colons if a line break is present between them. Javscript interprets line break as implicit semicolon.
  • It's always a best practice to add semi-colon at the end of the statement.

Comments

  1. Single line comments

// is used to comment a single line

  1. Multi line comments

/**/ is used to comment multiple lines.

Modern Mode

  • You must explictly declare with directive "use Strict" or 'use Strict' at the top of the script to tell the javascript should work in strict mode.

You can practice Javascript here with out any IDEs or code editors.