JavaScript Numbers

What are Numbers in JavaScript?

In JavaScript, numbers are a data type used to represent both:

Integers (like 10, -5, 1000)
Floating-point numbers (like 3.14, -0.01, 2.718)

In JavaScript, there is only one type for all numbers: number. (Unlike some languages that have different types for integers and floats.)

Creating Numbers

1. Using Numeric Literals

let x = 10; // Integer
let y = 3.14; // Floating-point number

2. Using the Number Object

let num = new Number(100);
console.log(num); // Output: [Number: 100]

Note: Using new Number() creates a Number object, not a primitive number. Mostly, primitive numbers are preferred.

Examples and Outputs

Example 1: Basic Numbers

let a = 5;
let b = 2.5;
console.log(a); // Output: 5
console.log(b); // Output: 2.5

Example 2: Arithmetic Operations

let x = 10;
let y = 4;
console.log(x + y); // Output: 14
console.log(x - y); // Output: 6
console.log(x * y); // Output: 40
console.log(x / y); // Output: 2.5
console.log(x % y); // Output: 2

Special Number Values

Value	Description	Example	Output
Infinity	Result of division by 0	5 / 0	Infinity
-Infinit Y	Negative division by 0	-5 / 0	-Infinit Y
NaN	"Not a Number" (Invalid calculation)	"abc" / 2	NaN

Example:

console.log(5 / 0); // Output: Infinity
console.log(-5 / 0); // Output: -Infinity
console.log("abc" / 2); // Output: NaN

Checking Numbers

1. isNaN()

Checks if a value is NaN (Not a Number).

console.log(isNaN(100)); // Output: false
console.log(isNaN("hello")); // Output: true

2. isFinite()

Checks if a number is finite.

console.log(isFinite(10)); // Output: true
console.log(isFinite(Infinity)); // Output: false

Number Methods

Method	Description	Example	Output
toString()	Converts number to string	(123).toString()	"123"
toFixed(n)	Rounds number with n decimals	(3.14159).toFixed(2)	"3.14"
toExponential()	Converts to exponential form	(123456).toExponential 5	"1.23456e+"1.23456e+5"
toPrecision(n)	Formats to specified length	(3.14159).toPrecision(4)	"3.142"

Example:

let num = 5.6789;
console.log(num.toFixed(2)); // Output: "5.68"
console.log(num.toString()); // Output: "5.6789"
console.log(num.toExponential(2)); // Output: "5.68e+0"
console.log(num.toPrecision(3)); // Output: "5.68"

Number Constants

JavaScript provides built-in constants related to numbers:

Constant	Value	Description
Number.MAX_VALUE	Largest possible number
Number.MIN_VALUE	Smallest positive number
Number.POSITIVE_INFINITY	Infinity
Number.NEGATIVE_INFINITY	-Infinity
Number.NaN	NaN

Example:

console.log(Number.MAX_VALUE); // Output: 1.7976931348623157e+308
console.log(Number.MIN_VALUE); // Output: 5e-324

Type Conversion to Numbers

You can convert other types into numbers using:

Function	Example	Output
Number()	Number("123")	123
parseInt()	parseInt("123px")	123
parseFloat()	parseFloat("3.14meters")	3.14

Example:

console.log(Number("123")); // Output: 123
console.log(parseInt("456abc")); // Output: 456
console.log(parseFloat("3.14xyz")); // Output: 3.14