// Form Validation
function validate_required(field,alerttxt)  // required fields
{
with (field)
  {
  if (value==null||value=="")
    {
    alert(alerttxt);return false;
    }
  else
    {
    return true;
    }
  }
}

function validate_phone(field,alerttxt)  // validate phone
{
with (field)
  {
  apos=value.indexOf("(");
  bpos=value.indexOf(")");
  cpos=value.indexOf("-");
  len=value.length;
  if (apos!=0||bpos!=4||cpos!=8||len<13)
    {alert(alerttxt);return false;}
  else {return true;}
  }
}

function validate_date(field,alerttxt)  // validate date
{
with (field)
  {
  apos=value.indexOf("/");
  bpos=value.indexOf("/",3);
  len=value.length;
  if (apos!=2||bpos!=5||len<10)
    {alert(alerttxt);return false;}
  else {return true;}
  }
}

function validate_age(field,alerttxt)  // validate age
{
with (field)
  {
  if (value < 8 || value > 70)
    {
    alert(alerttxt);return false;
    }
  else
    {
    return true;
    }
  }
}

function validate_email(field,alerttxt)  // validate email
{
with (field)
  {
  apos=value.indexOf("@");
  dotpos=value.lastIndexOf(".");
  if (apos<1||dotpos-apos<2)
    {alert(alerttxt);return false;}
  else {return true;}
  }
}

function validate_form(thisform)  // validate the form when submitted
{
with (thisform)
  {
  if (validate_required(first_name,"First Name must be filled out!")==false)
    {first_name.focus();return false;}
  if (validate_required(last_name,"Last Name must be filled out!")==false)
    {last_name.focus();return false;}
  if (validate_required(email,"Valid email must be filled out!")==false)
    {email.focus();return false;}
  if (validate_age(age,"Age must be between 8 and 70")==false)
    {age.focus();return false;}
  if (validate_email(email,"Not a valid e-mail address!")==false)
    {email.focus();return false;}
  if (validate_required(age,"Your age must be filled out!")==false)
    {age.focus();return false;}
  }
}