//This script and many more are available free online at
//The JavaScript Source!! http://javascript.internet.com
//Original:  Fred P

// Compare two options within a list by VALUES
function compareOptionValues(a, b) { 
  // Radix 10: for numeric values
  // Radix 36: for alphanumeric values
  var sA = parseInt( a.value, 36 );  
  var sB = parseInt( b.value, 36 );  
  return sA - sB;
}

// Compare two options within a list by TEXT
function compareOptionText(a, b) { 
  // Radix 10: for numeric values
  // Radix 36: for alphanumeric values
  var sA = parseInt( a.text, 36 );  
  var sB = parseInt( b.text, 36 );  
  return sA - sB;
}

// Dual list move function
function moveDualList( srcList, destList, moveAll ) {
  // Do nothing if nothing is selected
  if (  ( srcList.selectedIndex == -1 ) && ( moveAll == false)) {
    return;
  }

  newDestList = new Array( destList.options.length );
  var len = 0;
  for( len = 0; len < destList.options.length; len++ ) {
    if ( destList.options[ len ] != null ) {
       newDestList[len] = new Option(destList.options[len].text, destList.options[len].value, destList.options[len].defaultSelected, destList.options[len].selected);
    }
  }

  for( var i = 0; i < srcList.options.length; i++ ) { 
    if ( srcList.options[i] != null && (srcList.options[i].selected == true || moveAll)) {
       // Statements to perform if option is selected
       // Incorporate into new list
       newDestList[ len ] = new Option( srcList.options[i].text, srcList.options[i].value, srcList.options[i].defaultSelected, srcList.options[i].selected);
       len++;
    }
  }


  // Sort out the new destination list
  //newDestList.sort( compareOptionValues );   // BY VALUES
  newDestList.sort( compareOptionText );   // BY TEXT
  // Populate the destination with the items from the new array
  for ( var j = 0; j < newDestList.length; j++ ) {
    if ( newDestList[ j ] != null ) {
      destList.options[ j ] = newDestList[ j ];
    }
  }


  // Erase source list selected elements
  for(var i = srcList.options.length - 1; i >= 0; i--) { 
    if (srcList.options[i] != null && ( srcList.options[i].selected == true || moveAll)) {
       // Erase Source
       //srcList.options[i].value = "";
       //srcList.options[i].text  = "";
       srcList.options[i]       = null;
    }
  }
}