function trim(str)
  {
     return str.replace(/^\s+\s+$/g,'')
  }

function isemail(email)
 {
  if (!(/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(email.value)))
  {
    alert("The email you have entered is not correct");
    email.focus();
    return false;

  }
  else
  {
          return true;
  }
 }

function chk_sendd(sender_name,sender_email,to,subject,msg)
  {
      if(trim(sender_name.value)== "")
       {
               alert("Enter your name");
               sender_name.focus();
               return false;
       }
      else if(trim(sender_email.value)== "")
       {
               alert("Enter your email please");
               sender_email.focus();
               return false;
       }
      else if(!isemail(sender_email))
      {
          return false;
      }
       else if(trim(subject.value)== "0")
       {
               alert("Please select email subject");
               subject.focus();
               return false;
       }
       else if(trim(msg.value)== "")
       {
               alert("Please write a message");
               msg.focus();
               return false;
       }
  }