easyui 键盘控制tree 上下

 $.extend($.fn.tree.methods, {
     highlight: function(jq, target){
         return jq.each(function(){
             $(this).find('.tree-node-hover').removeClass('tree-node-hover');
             $(target).addClass('tree-node-hover');
         })
     },
     nav: function(jq){
         return jq.each(function(){
             var t = $(this);
             t.attr('tabindex',0);
             t.unbind('.tree').bind('keydown.tree', function(e){
                 var curr = getCurr();
                 if (!curr.length){return}
                 if (e.keyCode == 40){    // down
                     var li = getNext(curr);
                     if (li.length){
                         t.tree('highlight', li[0]);
                     }
                 } else if (e.keyCode == 38){    // up
                     var li = getPrev(curr);
                     if (li.length){
                         t.tree('highlight', li[0]);
                     }
                 } else if (e.keyCode == 13){
                     t.tree('select', curr[0]);
                 } else if (e.keyCode == 39){    // right
                     if (!t.tree('isLeaf', curr[0])){
                         t.tree('expand', curr[0]);
                     }
                 } else if (e.keyCode == 37){    // left
                     if (!t.tree('isLeaf', curr[0])){
                         t.tree('collapse', curr[0]);
                     }
                 }
                 e.preventDefault();
             }).bind('mouseover.tree', function(e){
                 var node = $(e.target).closest('div.tree-node');
                 if (node.length){
                     t.find('.tree-node-hover').each(function(){
                         if (this != node[0]){
                             $(this).removeClass('tree-node-hover');
                         }
                     })
                 }
             });
             function getCurr(){
                 var n = t.find('.tree-node-hover');
                 if (!n.length){
                     n = t.find('.tree-node-selected');
                 }
                 return n;
             }
             function getNext(curr){
                 var n = $();
                 var node = t.tree('getNode', curr[0]);
                 if (t.tree('isLeaf', node.target)){
                     n = curr.parent().next().children('div.tree-node');
                     if (!n.length){
                         var p = t.tree('getParent', curr[0]);
                         if (p){
                             n = $(p.target).parent().next().children('div.tree-node');
                         }
                     }
                 } else {
                     if (node.state == 'closed'){
                         n = curr.parent().next().children('div.tree-node');
                     } else {
                         var cc = t.tree('getChildren', curr[0]);
                         if (cc.length){
                             n = $(cc[0].target);
                         }
                     }

                 }
                 return n;
             }
             function getPrev(curr){
                 var n = curr.parent().prev().children('div.tree-node');
                 if (n.length){
                     var node = t.tree('getNode', n[0]);
                     if (node.state == 'open'){
                         var cc = t.tree('getChildren', node.target);
                         if (cc.length){
                             n = $(cc[cc.length-1].target);
                         }
                     }
                 } else {
                     var p = t.tree('getParent', curr[0]);
                     if (p){
                         n = $(p.target);
                     }
                 }
                 return n;
             }
         })
     }
 })

$('#tt').tree('nav');