JavaScript - isNaN() method

revision:

Category : number

The Number.isNaN() static method determines whether the passed value is the number value NaN, and returns false if the input is not of the Number type. It is a more robust version of the original, global isNaN() function.

Syntax : 

        Number.isNaN(value)

Parameters:

value : required. The value to be tested for NaN.

Examples:

        function typeOfNaN(x) {
            if (Number.isNaN(x)) {
              return 'Number NaN';
            }
            if (isNaN(x)) {
              return 'NaN';
            }
        }
        console.log(typeOfNaN('100F'));
          // Expected output: "NaN"
        console.log(typeOfNaN(NaN));
          // Expected output: "Number NaN"

Practical examples

example: using the isNaN() method

code: 
                    <div>
                        <p id="NaN-1"></p>
                        <p id="NaN-2"></p>
                        <p id="NaN-3"></p>
                        <p id="NaN-4"></p>
                    </div>
                    <script>
                        document.getElementById("NaN-1").innerHTML = " Number.isNaN(NaN) : " + Number.isNaN(NaN); // true
                        document.getElementById("NaN-2").innerHTML = " Number.isNaN(Number.NaN) : " + Number.isNaN(Number.NaN); // true
                        document.getElementById("NaN-3").innerHTML = " Number.isNaN(0 / 0) : " + Number.isNaN(0 / 0); // true
                        document.getElementById("NaN-4").innerHTML = " Number.isNaN(37) : " + Number.isNaN(37); // false
                    </script>

example: Number.isNaN() method returns true if a value is NaN and of a datatype number, otherwise false

code: 
                    <div>
                        <p id="NaN-5"></p>
                    </div>
                    <script>
                        let result =
                            "Is 123 NaN? " + Number.isNaN(123) + "<br>" +
                            "Is -123 NaN? " + Number.isNaN(-1.23) + "<br>" +
                            "Is '123' NaN? " + Number.isNaN('123') + "<br>" +
                            "Is 0/0 NaN? " + Number.isNaN(0 / 0);
                        document.getElementById("NaN-5").innerHTML = result;
                    </script>

example: Number.isNaN() returns true if a value is NaN and of datatype Number, otherwise false.

code: 
                    <div>
                        <p id="NaN-6"></p>
                    </div>
                    <script>
                        let result1 =
                            "Is 5-2 NaN? " + Number.isNaN(5-2) + "<br>" +
                            "Is 0 NaN? " + Number.isNaN(0) + "<br>" +
                            "Is 'Hello' NaN? " + Number.isNaN('Hello') + "<br>" +
                            "Is '2005/12/12\ NaN? " + Number.isNaN('2005/12/12') + "<br>" +
                            "Is ' ' NaN? " + Number.isNaN('');
                        document.getElementById("NaN-6").innerHTML = result1;
                    </script>