JavaScript中的变量作用域(Dojo)

我有以下代码:

<div dojoType="dijit.form.Button">
    <script type="dojo/method" event="onClick" args="evt">
        console.dir(lastSelectedItem);
    </script>
    Rename
</div>

<div dojoType="dojo.data.ItemFileReadStore" url="/js/treeData.json" jsId="ordJson"></div>

<div dojoType="dijit.tree.ForestStoreModel" rootLabel="Order" store="ordJson" jsId="ordModel"></div>

<div dojoType="dijit.Tree" id="ordTree" model="ordModel">
    <script type="dojo/method" event="onClick" args="item">
        lastSelectedItem = item;
    </script>
</div>

谢谢。