JavaScript isFinite()

Check if a number is finite:

let result = isFinite(123);

let result = isFinite("123");

Description

The isFinite() method returns true if a value is a finite number.

Infinite (not finite) values are Infinity, -Infinity, or NaN

isFinite() returns true if a value is a finite number.

Number.isFinite() returns true if a number is a finite number.

In other words:

isFinite() converts the value to a number before testing it.

// This returns true
isFinite(123)

// This returns false
Number.isFinite("123")

isFinite(value)

Parameter	Description
value	Required. The value to be tested.

Type	Description
A boolean.	`false` if the value is Infinity, -Infinity, or NaN. Otherwise `true`.

Check if a number is finite:

isFinite(-1.23);
isFinite(5-2);
isFinite(0);

isFinite("Hello");
isFinite("2005/12/12");

isFinite() is an ECMAScript1 (ES1) feature.

ES1 (JavaScript 1997) is fully supported in all browsers:


Chrome	Edge	Firefox	Safari	Opera	IE
Yes	Yes	Yes	Yes	Yes	Yes