JavaScript Data Types

In this tutorial, you will learn about the different data types available in JavaScript with the help of examples.

JavaScript variables can hold numerous data types: numbers, strings, objects, and more:

As recommended by the name, data types refer to sorts of data that you can use in your program. For instance,

const x = 5;
const y = "Hello";

Here,

• 5 is an integer data.
• “Hello” is a string data.

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JavaScript Data Types

There are eight fundamental data types in JavaScript. They are:

Data Types	Description	Example
String	represents textual data	‘hello’, “hello world!” etc
Number	an integer or a floating-point number	3, 3.234, 3e-2 etc.
BigInt	an integer with arbitrary precision	900719925124740999n , 1n etc.
Boolean	Any of two values: true or false	true and false
undefined	a data type whose variable is not initialized	let a;
null	denotes a null value	let a = null;
Symbol	data type whose instances are unique and immutable	let value = Symbol(‘hello’);
Object	key-value pairs of collection of data	let student = { };

Here, all data types aside from Object are primitive data types, while Object is non-primitive.

Note: The Object data type (non-primitive sort) can store assortments of data, whereas the primitive data type can just store a single data.

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JavaScript String

String is used to store text. In JavaScript, strings are surrounded by quotes:

• Single quotes: ‘Hello’
• Double quotes: “Hello”
• Backticks: Hello

For example,

//strings example
const name = 'haroon';
const name1 = "sohail";
const result = `The names are ${name} and ${name1}`;

Single quotes and double quotes are basically the equivalents and you can use both of them.

Backticks are generally used when you need to incorporate variables or articulations into a string. This is finished by wrapping variables or articulations with ${variable or expression} as shown above.

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JavaScript Number

The number represents integer and floating numbers (decimals and exponentials). For example,

const number1 = 3;
const number2 = 3.433;
const number3 = 3e5 // 3 * 10^5

A number type can also be +Infinity, -Infinity, and NaN (not a number). For example,

const number1 = 3/0;
console.log(number1); // returns Infinity

const number2 = -3/0;
console.log(number2); // returns -Infinity

// strings can't be divided by numbers
const number3 = "abc"/3; 
console.log(number3);  // returns NaN

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JavaScript BigInt

In JavaScript, Number sort can just speak to numbers under (2⁵³  – 1) and more than – (2⁵³ – 1). However, if you need to use a larger number than that, you can use the BigInt data type.

A BigInt number is made by annexing n to the furthest limit of a number. For instance,

// BigInt value
const value1 = 900719925124740998n;

// Adding two big integers
const result1 = value1 + 1n;
console.log(result1); // returns "900719925124740999n"

const value2 = 900719925124740998n;

// Error! BitInt and number cannot be added
const result2 = value2 + 1; 
console.log(result2); 

Output

900719925124740999n
Uncaught TypeError: Cannot mix BigInt and other types

Note: BigInt was introduced in the newer version of JavaScript and is not supported by many browsers including Safari. Visit JavaScript BigInt support to learn more.

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JavaScript Boolean

This data type represents logical entities. Boolean speaks to one of two qualities: true or false. It is simpler to consider it a yes/no switch. For instance,

const dataChecked = true;
const valueCounted = false;

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JavaScript undefined

The unclear data type speaks to value that isn’t assigned. If a variable is announced however the worth isn’t assigned, at that point, the value of that variable will be undefined. For instance,

let name;
console.log(name); // returns undefined

It is also possible to explicitly assign a variable value undefined. For example,

let name = undefined;
console.log(name); // returns undefined

Note: It is prescribed not to expressly appoint vague to a variable. Typically, invalid is used to appoint ‘obscure’ or ‘void’ worth to a variable.

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JavaScript null

In JavaScript, null is a special value that represents an empty or unknown value. For example,

const number = null;

The code above suggests that the number variable is empty.

Note: null is not the same as NULL or Null.

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JavaScript Symbol

This data type was presented in a more up to date form of JavaScript (from ES2015).

A worth having the data type Symbol can be referred to as a symbol value. the symbol is an immutable primitive worth that is extraordinary. For instance,

// two symbols with the same description

const value1 = Symbol('hello');
const value2 = Symbol('hello');

Though value1 and value2 both contain ‘hello’, they are different as they are of the Symbol type.

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JavaScript Object

An object is a complex data type that allows us to store collections of data. For example,

const student = {
    firstName: 'haroon',
    lastName: null,
    class: 10
};

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JavaScript Type

JavaScript is a dynamically typed (loosely typed) language. JavaScript consequently decides the variables’ data type for you.

It also implies that a variable can be of one data type and later it can be changed to another data type. For instance,

// data is of undefined type
let data;

// data is of integer type
data = 5;

// data is of string type
data = "JavaScript Programming";

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JavaScript typeof

To find the type of a variable, you can use the typeof operator. For example,

const name = 'haroon';
typeof(name); // returns "string"

const number = 4;
typeof(number); //returns "number"

const valueChecked = true;
typeof(valueChecked); //returns "boolean"

const a = null;
typeof(a); // returns "object"

Notice that typeof returned “object” for the null type. This is a known issue in JavaScript since its first release.

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