The isNaN() function decides whether a value is an illegal number(Not-a-Number). Return Value true if the value converted to the Number type is the NaN, otherwise false. Web Joomla

isNaN() function determines the value which is passed to the function is a non-numeric or not. If the value is numeric it returns false else it returns true. ex: document.write(isNaN(123)); falsedocument.write(isNaN(-1.23)); falsedocument.write(isNaN('hello')); true