Number.isFinite()
Number.isFinite() 方法會判斷傳入的值是否為有限數（finite number）。
嘗試一下
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() (en-US) 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 |
|---|
| ECMAScript Language Specification # sec-number.isfinite |
瀏覽器相容性
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參見
- The
Numberobject it belongs to. - The global function
isFinite(en-US).