The isFinite()
function checks whether the passed value is a finite number.
Example
// check if 100 is a finite number
console.log(isFinite(100));
// Output: true
// check if NaN is a finite number
console.log(isFinite(NaN));
// Output: false
isFinite() Syntax
The syntax of the isFinite()
function is:
isFinite(testValue)
isFinite() Parameters
The isFinite()
function takes in:
- testValue - value to be tested for finiteness.
isFinite() Return Value
The isFinite()
function returns
false
- if the argument isInfinity
orNaN
orundefined
true
- for all other arguments
Example 1: JavaScript isFinite()
// check whether 5463 is finite or not
console.log(isFinite(5463));
// Output: true
In the above example, we have used isFinite()
to check whether the given value is finite or not. The output is true
, as 5463 is a finite number.
Example 2: isFinite() With Infinity and undefined
// check whether Infinity is finite or not
console.log(isFinite(Infinity));
// Output: false
// check whether undefined is finite or not
console.log(isFinite(undefined));
// Output: false
Example 3: isFinite() With NaN and null
// check whether NaN is finite or not
console.log(isFinite(undefined));
// Output: false
// check whether null is finite or not
console.log(isFinite(null));
// Output: true
Note: In JavaScript, isFinite()
is a top-level function because it is not associated with any object or class, and we can call it from anywhere without creating an instance.
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