JavaScript Introduction

Java Script is the language for scripting inside a web page in the browser. Despite the name and similarity in syntax it is not related to Java at all. It is related to ECMAScript.

JavaScript is primarily responsible for all the interactivity you see on web pages.

JavaScript is typeless and does not require variable declaration. This means that variables declared in the language can actually accept any kind of data. and you just need to write a variable name and it will be created at that point.
JavaScript is responsible for the drop down menus, animations , chat systems etc that are there on the web. AJAX is a JavaScript technology that allows web pages to query servers from the client.

Over a period of time many JavaScript libraries have developed that simplify and automate various tasks. JQuery, AngularJS, Node.js etc are a few. We shall talk about them later.

JavaScript is an incredibly flexible language as we shall see.

JavaScript Data Types 
In JavaScript data is either an object, a primitive value or a function.
A primitive value would be one of the following:
undefined, null, Boolean, number or string.

The following built in objects exist in JavaScript.
Object, Function, Array, String, Boolean, Number, Math, Date, RegExp, JSON and Error objects.

Next step JavaScript Identifiers.