wiki/content/20200923153425-number.md

---
date: 2020-09-23
id: adb898a3-6623-4bd5-92e6-408287d8cb31
title: JavaScript Number library
---

# ES6

## .EPSILON

Compares floating point numbers with a tolerance for rounding errors.

## .isInteger(num)

``` javascript
console.log(Number.isInteger(1.05)) // false
console.log(Number.isInteger(1)) // true
console.log(Number.isInteger(-3.1)) // false
console.log(Number.isInteger(-3)) // true
```

## .isNaN

Checks whether num is the value NaN. In contrast to the global function
isNaN(), it doesn’t coerce its argument to a number and is therefore
safer for non-numbers:

``` javascript
console.log(isNaN('???')) // true
console.log(Number.isNaN('???')) // false
```

## .isFinite

Determines whether the passed value is a finite number

``` javascript
console.log(Number.isFinite(Infinity)) // false
console.log(Number.isFinite(123)) // true
```