移动option

(function() {  var leftSelectObj = document.getElementById(‘leftSelect‘);  var leftBtnUp = document.getElementById(‘left_btn_up‘);  var leftBtnDown = document.getElementById(‘left_btn_down‘);  var rightSelectObj = document.getElementById(‘rightSelect‘);  var rightBtnUp = document.getElementById(‘right_btn_up‘);  var rightBtnDown = document.getElementById(‘right_btn_down‘);  var btnLeft = document.getElementById(‘btn_left‘);  var btnLeftAll = document.getElementById(‘btn_left_all‘);  var btnRight = document.getElementById(‘btn_right‘);  var btnRightAll = document.getElementById(‘btn_right_all‘);

  leftBtnDown.onclick = function() {    var index = leftSelectObj.selectedIndex;    if(index !== -1) {      if(index === leftSelectObj.length - 1) {        leftSelectObj.insertBefore(leftSelectObj.children[index], leftSelectObj.children[0]);      } else {        leftSelectObj.insertBefore(leftSelectObj.children[index], leftSelectObj.children[index + 2]);      }    }  };

  leftBtnUp.onclick = function() {    var index = leftSelectObj.selectedIndex;    if(index !== -1) {      if(index === 0) {        leftSelectObj.appendChild(leftSelectObj.children[index]);      } else {        leftSelectObj.insertBefore(leftSelectObj.children[index], leftSelectObj.children[index - 1]);      }    }  };

  btnRight.onclick = function() {    var index = leftSelectObj.selectedIndex;    if(index !== -1) {      rightSelectObj.appendChild(leftSelectObj.children[index]);    }  };

  btnRightAll.onclick = function() {    for(var i = 0; i < leftSelectObj.length; ++i) {      rightSelectObj.appendChild(leftSelectObj.children[i]);      --i;    }  };})();