function addProduct(productID) {
  
 var currentQty = parseFloat(document.getElementById('felt'+productID).value);
 var itemPrice = document.getElementById('prisprstyk_felt'+productID).value;
 var itemName = document.getElementById('title_felt'+productID).value;
 if(currentQty > 10000 || isNaN(currentQty)) {
  alert('Kun tal under 10001 er tilladt');
  document.getElementById('felt'+productID).value = 0;
  currentQty = 0;
 }
 
 for(i=0; i< orderLines.length; i++) {
  var item = orderLines[i].split(';')[0]; 
  //Hvis varen eksisterer i kurven
  if(item == productID) {
   if(currentQty > 0) {
    //Hvis antal > 0 => Slet og opret varelinie med nyt antal
    //alert('Varen eksisterer i kurven - antal opdateres');
    orderLines.splice(i,1);
    orderLines.push(productID+';'+itemName+' '+currentQty+' stk. a '+itemPrice);
    var exists = 1;
   } else {
    //Hvis antal <0 => Slet varen
    //alert('Varen eksisterer i kurven - og fjernes');
    orderLines.splice(i,1);
    var exists = 1;
   }
  } 
 }
 
 //Hvis varen ikke eksisterer i kurven
 if(exists != 1) {
  //alert('Varen eksisterer ikke i kurven');
  orderLines.push(productID+';'+itemName+' '+currentQty+' stk. a '+itemPrice);
  exists = 0;
 }
 
//Opret nyt array
var visibleOrderLines = new Array(); 
 for(i=0; i< orderLines.length; i++) {
  var newOrderLine = orderLines[i].split(';')[1];
  visibleOrderLines.push(newOrderLine);
 } 
 //alert(visibleOrderLines);
 var totalOrderLines = visibleOrderLines.join('\n');
 
 document.getElementById('orderlines').value = totalOrderLines;
 //alert(document.getElementById('orderlines').value);
 //Total price for this amount of this product
 var price = parseFloat(document.getElementById('prisprstyk_felt'+productID).value.replace('kr. ', ''));
 var price_qty = price * currentQty;
 document.getElementById('pris_felt'+productID).value = price_qty;
 
 var totalCount = 0;
 var totalAmount = 0;
 var re = new RegExp("(^| )" + 'com-input-qty' + "( |$)");
 var re2 = new RegExp("(^| )" + 'com-input-price' + "( |$)");
 var foo = document.all ? document.all : document.getElementsByTagName('input');

 //Calculate total quantity
 for (i = 0; i < foo.length; i++) {
   if (re.test(foo[i].className)) {
     totalCount += parseFloat(foo[i].value);
   }
 }
 
 //Calculate total amount
 for (j = 0; j < foo.length; j++) {
   if (re2.test(foo[j].className)) {
     totalAmount += parseFloat(foo[j].value.replace('kr. ', ''));
   }
 }
 
 document.getElementById('com-total-qty').value = totalCount;
 document.getElementById('com-total-amount').value = totalAmount;
}