`Number.isFinite()` is the best way to check for a number in JavaScript

Need a simple way to check for a number in JavaScript, but don’t want `NaN` or `Infinity`? Use `Number.isFinite()` instead of `typeof`.

1 min readDec 5, 2019

Hi Sumer Singh, thanks for taking the time to read my article and for your insightful response!

You are exactly right, Number.isFinite() is the easiest way to check for a finite number, as it excludes NaN, Infinity, and -Infinity:

I clarified my article on checking for a JavaScript number to recommend Number.isFinite() and to point out that there is the global isFinite() function, which does perform type coercion if that behavior is desired:

How to check for a number in JavaScript

Numbers are a primitive type in JavaScript, but just using typeof will not differentiate numbers from NaN or Infinity.

medium.com

Thanks again for supporting my blog and sharing your insight!

It is much appreciated!!! 😁

`Number.isFinite()` is the best way to check for a number in JavaScript

Need a simple way to check for a number in JavaScript, but don’t want `NaN` or `Infinity`? Use `Number.isFinite()` instead of `typeof`.

How to check for a number in JavaScript

Numbers are a primitive type in JavaScript, but just using typeof will not differentiate numbers from NaN or Infinity.

Written by Dr. Derek Austin 🥳

Responses (1)

Number.isFinite() is the best way to check for a number in JavaScript

Need a simple way to check for a number in JavaScript, but don’t want NaN or Infinity? Use Number.isFinite() instead of typeof.

How to check for a number in JavaScript

Numbers are a primitive type in JavaScript, but just using typeof will not differentiate numbers from NaN or Infinity.

Written by Dr. Derek Austin 🥳

Responses (1)

`Number.isFinite()` is the best way to check for a number in JavaScript

Need a simple way to check for a number in JavaScript, but don’t want `NaN` or `Infinity`? Use `Number.isFinite()` instead of `typeof`.