new Date instances will returns the timestamp and it won't be NaN for any valid Date. So isNaN(new Date()) will return false.
<!DOCTYPE html>
<html>
<head>
<title>Welcome to LearnKode - A code learning platform</title>
</head>
<body>
<p>The isNaN() function returns true if the value is NaN (Not-a-Number), and false if not.</p>
<button onclick="checkNumber()">Check the value</button>
<p id="sample"></p>
<script>
function checkNumber() {
var a = isNaN(new Date()) + "<br>";
var b = isNaN(new Date().toString()) + "<br>";
var c = isNaN("blabla") + "<br>";
numbers=a+b+c;
document.getElementById("sample").innerHTML = numbers;
}
</script>
</body>
</html>
