var name = "Name";

var email = "email";

var comment = "Comment";

var warning = "";

var flag=0;



function checkform() {



if (document.mail.name.value == "")

  {

   warning=warning + "Please input Your Name";

   flag=1;

  }

if (document.mail.email.value == "")

  {

   if (flag==0) {

   warning=warning + "Please input Your E-mail";

   flag=2;

   }

   if (flag==1) {

   warning=warning + ", Your Email";

   flag=2;

   }

  }

if (document.mail.comment.value == "")

  {

   if(flag==1 || flag==2) {

   warning=warning + ", Comment";

   flag=3;

   }

   if (flag==0) {

   warning=warning + "Please input Your Comment";

   flag=3;

   }

  }



if (flag!=0) {

alert(warning);

flag=0;

warning="";

}

else {

document.mail.submit();

}

}