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Number.isFinite() 方法會判斷傳入的值是否為有限數(finite number)。

語法

Number.isFinite(value)

參數

value
The value to be tested for finiteness.

回傳值

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

說明

In comparison to the global isFinite() function, this method doesn't forcibly convert the parameter to a number. This means only values of the type number, that are also finite, return true.

範例

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

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

規範

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Number.isInteger' in that specification.
Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Number.isInteger' in that specification.
Draft  

瀏覽器相容性

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support19 Yes16 No159
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes16 Yes Yes Yes

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