Applies to: Global Object
The isNaN method is use to get a Boolean value that indicates whether a value is the reserved value NaN (not a number).
Syntax
isNaN(numvalue)
The numvalue argument is the value to be tested against NaN.
Return boolean
Returns a Boolean value that indicates whether a value is the reserved value NaN (not a number).
Example
The isNaN function returns true if the value is NaN, and false otherwise. You typically use this function to test return values from the parseInt and parseFloat methods.
Alternatively, a variable could be compared to itself. If it compares as unequal, it is NaN. This is because NaN is the only value that is not equal to itself.
See also: isFinite Method, NaN Property (Global), parseFloat Method, parseInt Method |
