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Number.isFinite

The Number.isFinite() method determines whether the passed value is a finite number — that is, it checks that a number is neither positive nor negative Infinity, since JavaScript has both.

Syntax

Number.isFinite(value)

Parameters

value
The value to be tested for finiteness.

Return value

A Boolean indicating whether or not the given value is a finite number.

Description

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.

Examples

Using isFinite

Number.isFinite(Infinity);  // false
Number.isFinite(NaN);       // false
Number.isFinite(-Infinity); // false

Number.isFinite(0);         // true
Number.isFinite(2e64);      // true

Number.isFinite('0');       // false, would've been true with
                            // global isFinite('0')
Number.isFinite(null);      // false, would've been true with
                            // global isFinite(null)

Polyfill

if (Number.isFinite === undefined) Number.isFinite = function(value) {
    return typeof value === 'number' && isFinite(value);
}

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
isFinite 19 12 16 No 15 9
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
isFinite ≤37 25 16 14 9 1.5
Server
Node.js
isFinite 0.10

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isFinite