Number Type

Unlike many other programming languages that separate integers and floating-point numbers into different types, JavaScript uses one unified Number type to account for numbers. This means you can work with whole numbers, decimals, and even special numeric values all under the same Number data type umbrella.

Here’s a basic example showing you integers, floating point numbers, and negative numbers are all of type number:

const wholeNumber = 50;
const decimalNumber = 4.5;
const negativeNumber = -7;
 
console.log(typeof wholeNumber); // number
console.log(typeof decimalNumber); // number
console.log(typeof negativeNumber); // number

JavaScript’s Number type includes various kinds of numeric values, ranging from simple integers and floating-point numbers to special cases like Infinity and NaN, or “Not a Number”. Let’s break down the main types you’ll encounter. Integers are whole numbers without any fractional or decimal part. They can be positive, negative, or zero. Here are some examples:

const positiveInteger = 100;
const negativeInteger = -25;
const zero = 0;
 
console.log(typeof positiveInteger); // number
console.log(typeof negativeInteger); // number
console.log(typeof zero); // number

Floating point numbers are numbers with decimal points. They’re often referred to as just “floats” by JavaScript developers. Floats are useful when you need more precision, such as when you’re dealing with measurements or currencies. Here are some examples:

const floatingPointNumber = 4.5;
const anotherFloat = 89.56;
const oneMoreFloat = 16.462;
 
console.log(typeof floatingPointNumber); // number
console.log(typeof anotherFloat); // number
console.log(typeof oneMoreFloat); // number

JavaScript can represent numbers that are beyond the maximum limit with Infinity. You’ll encounter this when you try to divide a number by zero or on rare occasions, exceed the upper boundary of the Number type. Here’s an example:

const infiniteNumber = 1 / 0;
console.log(infiniteNumber); // Infinity
console.log(typeof infiniteNumber); // number

Sometimes in JavaScript, some mathematical operations don’t result in a valid number. For instance, if you try to perform a mathematical operation on something that isn’t a number, you’ll get NaN, which stands for “Not a Number”:

const notANumber = 'hello world' / 2;
console.log(notANumber); // NaN

Surprisingly, the type of NaN is also Number:

const notANumber = 'hello world' / 2;
console.log(typeof notANumber); // number

Apart from the standard decimal system (base 10), JavaScript also supports numbers in different bases such as binary, octal, and hexadecimal. Binary is a base-2 system that uses only digits 1 and 0. Octal is a base-8 system that uses only digits 0 to 7. Hexadecimal is a base-16 system that uses digits 0 to 9 and letters a to f, like you see in CSS hex colors.