//common function for form validation

function trim(s)
{
   for (i=0; s.charAt(i)==' '; i++);
   var len = s.length;
   if (i>= len) return "";

   for (j=len-1; s.charAt(j)== ' '; j--);

   return s.substr(i, j-i+1);
}

function isEmptyString(s)
{
   for (i=0; s.charAt(i)==' '; i++);
   l=s.length;
   if (i>=l) {
     return true;
   }
   return false;
}

function isValidEmail(email)
{
    if (email== "") 
        return false;

    var last_char=email.length-1;
    var idx=email.indexOf("@");
    var idx2=email.lastIndexOf(".");
    var idx3=email.indexOf(" ");

    if (idx == -1 || idx== 0 || idx==last_char ||
        idx2 == -1 || idx2 == 0 || idx2 == last_char ||
        (idx2-1) <= idx || idx3  != -1) {
        return false;
    }

    return true;
}