isFinite()
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 (or will be coerced to) positive
or negative Infinity
or NaN
or undefined
;
otherwise, true
.
Description
isFinite
is a function property of the global 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
Using isFinite
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 |
---|
ECMAScript Language Specification # sec-isfinite-number |
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