isNaN Summary Checks if the value is NaN (Not a Number). Usage public bool isNaN() Returns true if the value is NaN and false if the value is not NaN. Description Checks if the System.Double value is NaN (Not a Number). Examples Basic Usage 1234import System; Console.log(Double.NaN.isNaN()); // trueConsole.log(100D.isNaN()); // false Share HTML | BBCode | Direct Link