Tuesday 28 August 2018

JavaScript: NaN: Not a Number

NaN stands for Not a Number, it is returned by Javascript when mathematical functions fail to return the result (or) when a function trying to parse a number fails.

var a = Math.sqrt(-1); // Return NaN
var b = parseInt("abrakadabra");  // Return NaN

Some Points to remember
a.   Zero divided by Zero results NaN
b.   Infinity divided by Inifnity results NaN
c.   Any Arithmetic operation on non-numeric operands that can’t be converted to number type leads to NaN.

How to test whether given variables value is NaN or not?
Javascript provides special function isNaN(variable), it return true if the given variable is NaN, else false.

nan.html

<!DOCTYPE html>

<html>

<head>
    <title>NaN example</title>
</head>

<body>
    <script type="text/javascript">
        var a = Math.sqrt(-1); // Return NaN
        var b = parseInt("abrakadabra"); // Return NaN
        var c = 10.09;

        document.write("a = " + a + "<br />");
        document.write("b = " + b + "<br />");
        document.write("c = " + c + "<br />");

        document.write("isNaN(a) = " + isNaN(a) + "<br />"); // Return true
        document.write("isNaN(b) = " + isNaN(b) + "<br />"); // Return true
        document.write("isNaN(c) = " + isNaN(c) + "<br />"); // Return false
    </script>
</body>

</html>

Note
a. If you perform any arithmetic operation with NaN, then the result is NaN.



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