The isNaN() function accepts a value and determines whether the given value is a number or not.If so, this method returns true else it returns false. You can also call this method using Number object.
Syntax
Its Syntax is as follows
isNAN(5655);
Example
<html>
<head>
<title>JavaScript Example</title>
</head>
<body>
<script type="text/javascript">
var result1 = parseFloat("Ef00A.D3");
document.write(isNaN(result1));
document.write('<br>');
var result2 = Math.log("welcome");
document.write(isNaN(result2));
document.write('<br>');
var result3 = Math.log(1254);
document.write(isNaN(result3));
</script>
</body>
</html>Output
true true false