function validate()
{ 
   if (document.registerForm.name.value == "")
   {
      alert ("Please, enter your Name.");
      document.registerForm.name.focus();
      return false;
   }
   if (document.registerForm.street.value == "")
   {
     alert ("Please, enter Street Address.");
     document.registerForm.street.focus();
     return false;
   }
   if (document.registerForm.city.value == "")
   {
    alert ("Please, enter City.");
     document.registerForm.city.focus();
     return false;
   }
   if (document.registerForm.state.value == "")
   {
     alert ("Please, enter State/Province.");
     document.registerForm.state.focus();
     return false;
   }
   if (document.registerForm.zip.value == "")
   {
     alert ("Please, enter Postal Code (ZIP).");
     document.registerForm.zip.focus();
     return false;
   }

   if (document.registerForm.email.value == "")
   {
     alert ("Please, enter your Email address.");
     document.registerForm.email.focus();
     return false;
   }
   
   if (isEmail(registerForm.email) == false){
       alert("Not valid E-mail address.")
       document.registerForm.email.focus();
       return false;
   } 
   
   if (document.registerForm.url.value == "")
   {
     alert ("Please, enter your Web site address.");
     document.registerForm.url.focus();
     return false;
   }
   
    if (isURL(registerForm.url) == false){
       alert("Not valid URL.")
       document.registerForm.url.focus();
       return false;
   }  

   if (document.registerForm.descr.value == "")
   {
     alert ("Please, enter brief description of your products.");
     document.registerForm.descr.focus();
     return false;
   } 
   if (document.registerForm.agree.checked == false)
   {
     alert ("You have to agree to the terms of this Application in order to proceed.");
     document.registerForm.agree.focus();
     return false;
   }

function isEmail(element){
      if (element.value.indexOf("@") != "-1" &&
          element.value.indexOf(".") != "-1"){
          return true;
      }else{
          return false;
      }
}

function isURL(element){
      if (element.value.substr(0,7).toLowerCase().indexOf("http://") != "-1" &&
          element.value.indexOf(".") != "-1"){
          return true;
      }else{
          return false;
      }
}

   return true;
 }