function isBlank(s) 
{
 var len=s.length
 var i
 for(i=0;i<len;++i) 
 {
  if(s.charAt(i)!=" ") return false
 }
 return true
}


function validate(fieldName,fieldValue) 
{
 if(isBlank(fieldValue)) 
 {
  alert(fieldName+" cannot be left blank.")
  return false
 }
 return true
}

function validateForm() 
{
 		
	
	if(!validate("The Phone field",document.feedback.phone.value))
	{
  		document.feedback.phone.focus()
		return false;
		
	}
	else if(isNaN(document.feedback.phone.value)) 
   	{ 
     	alert("Invalid data format.\n\n Only numbers are allowed."); 
     	document.feedback.phone.focus(); 
    	return (false); 
   	}
	
}