ext树为什么只显示根节点

Question

Ext.onReady(function(){
var a=[{id:'1',text:'1',leaf:true,expandable:true},
{id:'2',text:'2',leaf:true,expandable:true}
]
// shorthand
var Tree = Ext.tree;
var tree = new Tree.TreePanel({
el:'tree-div',
useArrows:true,
autoScroll:true,
animate:true,
enableDD:true,
containerScroll: true,
loader: new Tree.TreeLoader({
dataUrl:a
})
});

// set the root node
var root = new Tree.AsyncTreeNode({
    text: 'Ext JS',
    draggable:false,
    id:'source'
});
tree.setRootNode(root);

// render the tree
root.expand();
tree.render();

});

Answer 1

[code="js"]
Ext.onReady(function() {
var tree = new Ext.tree.TreePanel({
renderTo : Ext.getBody(),
useArrows : true,
autoScroll : true,
animate : true,
enableDD : true,
containerScroll : true,
loader : new Ext.tree.TreeLoader({
dataUrl : 'data.json'//这里是url资源,不能用变量的
}),
root : new Ext.tree.AsyncTreeNode({
text : 'Ext JS',
id : 'source'
})
});
});
[/code]

data.json的内容为
[code="js"]
[{id : '1',text : '1',leaf : true,expandable : true}, {id : '2',text : '2',leaf : true,expandable : true}]
[/code]

注意路径!