JavaScript NaN Property

　JavaScript Global Properties/Function

GlobalNaNThe property represents 'Not'-A-The value of 'Number' (not a number).

For example, if you try to multiply a number by a string, the returned value is 'NaN'.

The initial value of NaN is Not-A-Number, withNumber.NaNof the same value.

UsingisNaN()Function to check if the value is NaN.

Syntax:

NaN

var ans =　10　*　'Hello';
;document.getElementById('result').innerHTML = ans;

Browser Compatibility

All browsers fully support the NaN property:

Technical Details

More Examples

Check if the value is NaN using the isNaN() function:

var str = 'Hello world';
var ans = Number(str);　　　//　Convert a string to a number
;if (isNaN(ans)) {
　　　;document.getElementById('result').innerHTML = ans;
}

　JavaScript Global Properties/Function