var leftlist ;

        var rightlist ;

 

function init()

{

if(document.getElementById('left')){

         leftlist = document.getElementById('left');

         rightlist = document.getElementById('right');

       

}

 

}

function toLeft()

{

 init();

var newOption = document.createElement('option');

newOption.setAttribute('value', rightlist.item(rightlist.selectedIndex).getAttribute("value"));

newOption.text=rightlist.item(rightlist.selectedIndex).text;

leftlist.appendChild(newOption);

rightlist.remove(rightlist.selectedIndex);

       

}

function toRight()

{

     init();

var newOption = document.createElement('option');

newOption.setAttribute('value', leftlist.item(leftlist.selectedIndex).getAttribute("value"));

newOption.text=leftlist.item(leftlist.selectedIndex).text;

        rightlist.appendChild(newOption);

        leftlist.remove(leftlist.selectedIndex);

}