JS | CodersByte

INTRODUCTION

JavaScript (js) is a light-weight object-oriented programming language which is used by several websites for scripting the webpages. It is an interpreted, full-fledged programming language that enables dynamic interactivity on websites when applied to an HTML document. It was introduced in the year 1995 for adding programs to the webpages in the Netscape Navigator browser. Since then, it has been adopted by all other graphical web browsers. With JavaScript, users can build modern web applications to interact directly without reloading the page every time. The traditional website uses js to provide several forms of interactivity and simplicity.

Although, JavaScript has no connectivity with Java programming language. The name was suggested and provided in the times when Java was gaining popularity in the market. In addition to web browsers, databases such as CouchDB and MongoDB uses JavaScript as their scripting and query language.

SYNTAX

VARIABLE

A JavaScript variable is simply a name of storage location. There are two types of variables in JavaScript : local variable and global variable.

There are some rules while declaring a JavaScript variable (also known as identifiers).

Name must start with a letter (a to z or A to Z), underscore( _ ), or dollar( $ ) sign.
After first letter we can use digits (0 to 9), for example value1.
JavaScript variables are case sensitive, for example x and X are different variables.

OPERATORS

What is an Operator?

Let us take a simple expression 4 + 5 is equal to 9. Here 4 and 5 are called operands and ‘+’ is called the operator. JavaScript supports the following types of operators.

Arithmetic Operators
Comparison (Relational) Operators
Bitwise Operators
Logical Operators
Assignment Operators
Special Operators

ARITHMATIC OPERATORS

DATA TYPES

JavaScript provides different data types to hold different types of values. There are two types of data types in JavaScript.

Primitive data type
Non-primitive (reference) data type

JavaScript is a dynamic type language, means you don't need to specify type of the variable because it is dynamically used by JavaScript engine. You need to use var here to specify the data type. It can hold any type of values such as numbers, strings etc.