[Javascript] Is integer?

[lists at dwsasia.com (Peter Lauri)]

Best group member,

Is there any function that checks if something is an integer? I did not find
one and created this temporary function:

function isInteger(thenumber) {
	thenumberceil = Math.ceil(thenumber);
	if(thenumberceil>thenumber) return false;
	else return true;	
}

Why I actually need this is because I need to find out if a year is a "skott
year" (do not know the English word, but the years when February has 29 days
instead of 28). Is there any function for that? I created this temporary
function:

function isSkottYear(y) {
	yeardiv = y/4;
	if(isInteger(yeardiv)) return true;
	else return false;
}

There is probably better ways of doing this, are they?

Best regards,
Peter Lauri