Jaddo19:
My solution....

  var num=45;
  function isset(x){
  if(x=="undefined" ){
  return ' not defined';
 }else{
  return 'defined';
 }
 }
  isset(num);
 

always use camel case

modash:
I have an interesting challenge, write a program that gives you factorial of a number
E.g
5! = 5*4*3*2*1 = 120
4! = 4*3*2*1 = 24
3! = 3*2*1 = 6
2! = 2*1 = 2
1! = 1*1 = 1
0! = 1 (note the answer for zero factorial)

Should I drop the solution