function check_contact_us()
{
 contact_name=document.contact_us.contact_name.value;
 telephone_no=document.contact_us.telephone_no.value;
 mobile_no=document.contact_us.mobile_no.value;
 email=document.contact_us.email.value;
 
 
 if(contact_name=="")
 {
  alert("You cannot have contact name as empty !!")
  return false;
 }

if(email=="")
 {
   alert("You cannot have email address as empty !!")
   return false;
 }
 
 if(telephone_no!="")
  {

     var i;
     for (i = 0; i < telephone_no.length; i++)
     {
         // Check that current character is number.
         var c = telephone_no.charAt(i);
         if (((c < "0") || (c > "9")))
         {
           alert("Please enter numeric values only for telephone number");
           return false;
         }
     }
     // All characters are numbers.
     //return true;

  }
  
  if(mobile_no!="")
  {

     var i;
     for (i = 0; i < mobile_no.length; i++)
     {
         // Check that current character is number.
         var c = mobile_no.charAt(i);
         if (((c < "0") || (c > "9")))
         {
           alert("Please enter numeric values only for mobile number");
           return false;
         }
     }
     // All characters are numbers.
     //return true;

  }
  

 
 if (email != "")
    {

            var filter=/^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i;
            if (filter.test(email))
            {

                //return true;

            }

            else
            {
        		alert("Please input a valid email address!");
        		return false;
            }
   }
}