function swap_images(to, from){
 if(!document.getElementById) return false;
 if(!document.getElementById(to)) return false;
 if(!document.getElementById(from)) return false;
 document.getElementById(to).src = document.getElementById(from).src;
 return false;
}
function update_reserve(id, a){
 if(!document.getElementById) return false;
 if(!document.getElementById(id)) return false;
 if(a.options[a.selectedIndex].value.length != 0){
  document.getElementById(id).innerHTML = a.options[a.selectedIndex].value;
 }
 if(!document.getElementById('jav-style') && document.getElementById('jav-style').innerHTML != 'none') return false;
 if(!document.getElementById('jav-quant') && document.getElementById('jav-quant').innerHTML != 'none') return false;
 if(!document.getElementById('jav-total')) return false;
 if(document.getElementById('jav-quant').innerHTML != 'none'){
  document.getElementById('jav-total').innerHTML = document.getElementById('jav-quant').innerHTML * 18;
 } else {
  document.getElementById('jav-total').innerHTML = 0;
 }
}
function reserve_validate(){
 var valid = true;
 if(!document.getElementById) return false;
 if(document.getElementById('size')){
  var node = document.getElementById('size');
  if(node.options[node.selectedIndex].value.length == 0 || node.options[node.selectedIndex].value == 'none'){
   node.className = 'red';
   valid = false;
  } 
 }
 if(document.getElementById('quantity')){
  var node = document.getElementById('quantity');
  if(node.options[node.selectedIndex].value.length == 0 || node.options[node.selectedIndex].value == 'none'){
   node.className = 'red';
   valid = false;
  } 
 }
 if(document.getElementById('name')){
  var node = document.getElementById('name');
  if(node.value.length == 0){
   node.className = 'red';
   valid = false;
  } 
 }
 if(document.getElementById('email')){
  var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
  var node = document.getElementById('email');
  if(node.value.length == 0 || reg.test(node.value) == false) {
   alert('Your email address seems to be invalid.');
   node.className = 'red';
   valid = false;
  } 
 }
 return valid;
}