How to Check if a Value is NaN ?
Last Updated :
15 Feb, 2024
In JavaScript, you can check if a value is NaN
using the isNaN()
function or by using the Number.isNaN()
method. Both methods return a boolean value indicating whether the provided value is NaN
.
Using isNaN()
function:
isNaN(NaN); // true
isNaN(42); // false
isNaN("Hello"); // true (the string cannot be converted to a number)
Using Number.isNaN()
method:
Number.isNaN(NaN); // true
Number.isNaN(42); // false
Number.isNaN("Hello"); // false (the string is not a number, but it's not NaN)
Key Points:
isNaN()
function returns true
if the provided value is NaN
or if it cannot be converted into a number. This can sometimes lead to unexpected behavior, such as isNaN("Hello")
returning true
.
Number.isNaN()
method returns true
only if the provided value is NaN
. It does not perform any type coercion, so non-numeric values are considered false
.
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