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

function validate_form(thisform)
{
with (thisform)
{
if (validate_required(name,"Please include your name")==false)
  {email.focus();return false;}

if (validate_required(email,"Please include your email address")==false)
  {email.focus();return false;}  
  
if (validate_required(comments,"Please include a short message")==false)
  {email.focus();return false;}   
  
if (validate_email(email,"Not a valid e-mail address!")==false)
  {email.focus();return false;}
  
}
}

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