Number.isFinite()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.
The Number.isFinite() static method determines whether the passed value is a finite number — that is, it checks that a given value is a number, and the number is neither positive NaN.
Try it
console.log(Number.isFinite(1 / 0));
/ Expected output: false
console.log(Number.isFinite(10 / 5));
/ Expected output: true
console.log(Number.isFinite(0 / 0));
/ Expected output: false
Syntax
js
Number.isFinite(value)
Parameters
value-
The value to be tested for finiteness.
Return value
The boolean value true if the given value is a finite number. Otherwise false.
Examples
Using isFinite()
js
Number.isFinite(Infinity); / false
Number.isFinite(NaN); / false
Number.isFinite(-Infinity); / false
Number.isFinite(0); / true
Number.isFinite(2e64); / true
Difference between Number.isFinite() and global isFinite()
In comparison to the global isFinite() function, this method doesn't first convert the parameter to a number. This means only values of the type number and are finite return true, and non-numbers always return false.
js
isFinite("0"); / true; coerced to number 0
Number.isFinite("0"); / false
isFinite(null); / true; coerced to number 0
Number.isFinite(null); / false
Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-number.isfinite |