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The global isFinite() function determines whether the passed value is a finite number. If needed, the parameter is first converted to a number.

Syntax

isFinite(testValue)

Parameters

testValue
The value to be tested for finiteness.

Return value

false if the argument is positive or negative Infinity or NaN; otherwise, true.

Description

isFinite is a top-level function and is not associated with any object.

You can use this function to determine whether a number is a finite number. The isFinite function examines the number in its argument. If the argument is NaN, positive infinity, or negative infinity, this method returns false; otherwise, it returns true.

Examples

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

isFinite(0);         // true
isFinite(2e64);      // true
isFinite(910);       // true

isFinite(null);      // true, would've been false with the 
                     // more robust Number.isFinite(null)

isFinite('0');       // true, would've been false with the 
                     // more robust Number.isFinite("0")

Specifications

Specification Status Comment
ECMAScript 3rd Edition (ECMA-262) Standard Initial definition.
ECMAScript 5.1 (ECMA-262)
The definition of 'isFinite' in that specification.
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'isFinite' in that specification.
Standard  
ECMAScript Latest Draft (ECMA-262)
The definition of 'isFinite' in that specification.
Living Standard  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes Yes Yes Yes Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support Yes Yes Yes Yes Yes Yes Yes

See also

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