What is JavaScript?

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JavaScript is a programming language using in world wide web and used the client side of web page. JavaScript is a scripting language and write functions. It isn’t include networking and GUI features. JavaScript is high level language that has standard data structures, and the Document Object Model (DOM). JavaScript are similar java language in name, syntax, and respective standard libraries. JavaScript is a lightweight, interpreted programming language. It is designed for creating network-centric applications. JavaScript is very easy to implement because it is integrated with HTML. It is open and cross-platform.

Data Types

JavaScript is one of the most widely used programming languages (Front-end as well as Back-end). JavaScript’s  data types are Undefined, Number, BigInt, String, Boolean, Symbol. Undefined is assigned to all uninitialized variables, and is also returned when checking for object properties that do not exist. In a Boolean context, the undefined value is considered a false value. Numbers are represented in binary as IEEE-754 floating point doubles. BigInts can be used for arbitrarily large integers. A string in JavaScript is a sequence of characters. JavaScript provides a Boolean data type with true and false literals.

Example : function

function name(parameter1, parameter2, parameter3) {
// code to be executed

function is keyword and name is function name. Function names can contain letters, digits, underscores, and dollar signs (same rules as variables). Function parameters are listed inside in the function definition. Function arguments are the values received by the function when it is invoked. Inside the function, the arguments (the parameters) behave as local variables.


The ‘+’ operator is used for string concatenation and arithmetic addition. This may cause problems when inadvertently mixing strings and numbers. As a unary operator, it can convert a numeric string to a number. JavaScript supports the binary arithmetic operators, unary arithmetic operators, + operator can also be used to add (concatenate) strings, comparison operators, logical operators, type operators (typeof, instanceof), and bitwise operators.

JavaScript Objects

JavaScript provides a handful of native objects. JavaScript native objects are considered part of the JavaScript specification. JavaScript environment notwithstanding, this set of objects should always be available. There are Array, Date, Error, Math, Function, and Regular Expression.

Control Structures

JavaScript supports the structured programming syntax – if statements, while loops, switch statements, do while loops, etc. JavaScript only had function scoping with var; then block scoping was added with the keywords let and const.


JavaScript was initially created as a browser-only language, but it is now used in many other environments as well.
Today, JavaScript has a unique position as the most widely-adopted browser language, fully integrated with HTML/CSS. There are many languages that get “transpiled” to JavaScript and provide certain features. It is recommended to take a look at them, at least briefly, after mastering JavaScript.

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