Javascript and only one Checkbox - undefined

Question

for (i = 0; i < document.checks.user.length; i++) //for all check boxes
{
    if (document.checks.user[i].checked == true )
    {
        document.checks.submit()         


        

Answer 1

if(document.checks.user[0]) {
  //it's an array
}
else {
  //it's a single element
}