Datatypes And Type Casting

What are Datatypes?

In programming, data types is an important concept.

To be able to operate on variables, it is important to know something about the type.

For eg, 2 and 3 are numbers and when we add them, we get 5.

JavaScript is a loosely typed and dynamic language. Variables in JavaScript are not directly associated with any particular value type, and any variable can be assigned (and re-assigned) values of all types.

In Javascript, there are 7 primitive datatypes:

• boolean
• number
• string
• null
• undefined
• bigint
• symbol

Boolean

Boolean represents a logical entity and can have two values: true and false.

var a = true //Variable 'a' holds value of boolean type.

Number

The number type represents both integer and floating point numbers (decimals and exponentials).

A variable of number type can range between [-(2⁵³ − 1),(2⁵³ − 1)].

In addition to representing floating-point numbers, the number type has three symbolic values: +Infinity, -Infinity, and NaN (“Not a Number”).

var a = 2.3   //Variable 'a' holds value of number type.

var b = 2     //Variable 'b' holds value of number type.

String

String type is used to represent textual data. A string in JavaScript must be surrounded by quotes(double, single or backticks). It is a set of elements and each element in the string occupies a position.

var a = "Hello";  //Variable 'a' holds value of string type

Null

The Null type has exactly one value: null. Its a special value which can represent “nothing”, “empty” or “value unknown”.

var a = null   //Variable 'a' holds a value of null type.

Undefined

A variable that has been declared but not been assigned a value has the value undefined.

var a;  //Variable 'a' holds undefined

var b = undefined;  //Variable 'b' holds undefined

BigInt

BigInt type has been recently added to the language to represent integers of arbitrary length (numbers which cannot be represented in number type.

A BigInt value is created by appending n to the end of an integer. For e.g, 23n is a value of bigint type.

var a = 9324012456789012613321123n;

Symbol

A Symbol is a unique and immutable primitive value and may be used as the key of an Object property. It is used to create unique identifiers for objects.

Some more Datatypes:

Object

Object refers to a data structure containing data and instructions for working with the data. Objects sometimes refer to real-world things, for e.g, a vehicle etc.

Objects can contain many values in form of key-value pairs.

JavaScript objects are written with curly braces {}.

var a = {    //Variable 'a' stores an object which contains several key-value pairs.
    name: "Max",
    age: 20
}

Function

A function is a code snippet that can be called by other code or by itself, or a variable that refers to the function.

var a = function () {   //Variable 'a' holds a function
    console.log("Hello world!");
};

typeof Keyword

typeof is an operator which can easily help us to find the type of a certain variable.

For e.g console.log(typeof 30) prints number as output, signifying that the value 30 belongs to number type.

Type Conversion

JavaScript variables can be converted to a new variable and another data type by the use of a JavaScript function.

var a = true;
var b = String(true);
console.log(typeof a);   //prints boolean  
console.log(typeof b);  //prints string

Try the following example in the editor below.

Given an input string which represents a positive number, you have to print the next greater integer.

123

124