JavaScript: isNaN() function

Description

The isNaN function is used to determine whether a value is "NaN" (not a number) or not. isNaN is a top-level function and is not associated with any object.

Syntax

isNan(testvalue)

Parameters

testvalue: The value to evaluate.

Example: isNaN() function

The following example shows how to use isNaN() function.

JavaScript Code:

console.log(isNaN("Good Morning"));
console.log(isNaN("2009/01/01"));
console.log(isNaN(455));
console.log(isNaN(-9.34));
console.log(isNaN(15-12));
console.log(isNaN(0));

View the example in the browser

Live demo:

See the Pen isnan-function-1 by w3resource (@w3resource) on CodePen.

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