Almost anything can be represented in a tree structure. Examples include directories, organization hierarchies, biological classifications, countries, etc. The `Tree` component is a way of representing the hierarchical relationship between these things. You can also expand, collapse, and select a treeNode within a `Tree`.
| Property | Description | Type | Default | Version |
| --- | --- | --- | --- | --- |
| autoExpandParent | Whether to automatically expand a parent treeNode | boolean | true | |
| blockNode | Whether treeNode fill remaining horizontal space | boolean | false | |
| checkable | Adds a `Checkbox` before the treeNodes | boolean | false | |
| checkedKeys | (Controlled) Specifies the keys of the checked treeNodes (PS: When this specifies the key of a treeNode which is also a parent treeNode, all the children treeNodes of will be checked; and vice versa, when it specifies the key of a treeNode which is a child treeNode, its parent treeNode will also be checked. When `checkable` and `checkStrictly` is true, its object has `checked` and `halfChecked` property. Regardless of whether the child or parent treeNode is checked, they won't impact each other. | string\[] \| {checked: string\[], halfChecked: string\[]} | \[] | |
| checkStrictly | Check treeNode precisely; parent treeNode and children treeNodes are not associated | boolean | false | |
| defaultCheckedKeys | Specifies the keys of the default checked treeNodes | string\[] | \[] | |
| defaultExpandAll | Whether to expand all treeNodes by default | boolean | false | |
| defaultExpandedKeys | Specify the keys of the default expanded treeNodes | string\[] | \[] | |
| defaultExpandParent | auto expand parent treeNodes when init | bool | true | |
| defaultSelectedKeys | Specifies the keys of the default selected treeNodes | string\[] | \[] | |
| disabled | whether disabled the tree | bool | false | |
| draggable | Specifies whether this Tree is draggable (IE > 8) | boolean | false | |
| expandedKeys | (Controlled) Specifies the keys of the expanded treeNodes | string\[] | \[] | |
| filterTreeNode | Defines a function to filter (highlight) treeNodes. When the function returns `true`, the corresponding treeNode will be highlighted | function(node) | - | |
| selectable | whether can be selected | boolean | true | |
| selectedKeys | (Controlled) Specifies the keys of the selected treeNodes | string\[] | - | |
| showIcon | Shows the icon before a TreeNode's title. There is no default style; you must set a custom style for it if set to `true` | boolean | false | |
| showLine | Shows a connecting line | boolean | false | |
| treeData | treeNodes data Array, if set it then you need not to construct children TreeNode. (key should be unique across the whole array) | array\<{ key, title, children, \[disabled, selectable] }> | - | |
| icon | customize icon. When you pass component, whose render will receive full TreeNode props as component props | ReactNode/Function(props):ReactNode | - | |
| isLeaf | Determines if this is a leaf node(effective when `loadData` is specified) | boolean | false | |
| key | Used with (default)ExpandedKeys / (default)CheckedKeys / (default)SelectedKeys. P.S.: It must be unique in all of treeNodes of the tree! | string | internal calculated position of treeNode | |
| selectable | Set whether the treeNode can be selected | boolean | true | |
Before `3.4.0`: The number of treeNodes can be very large, but when `checkable=true`, it will increase the compute time. So, we cache some calculations (e.g. `this.treeNodesStates`) to avoid double computing. But, this brings some restrictions. **When you load treeNodes asynchronously, you should render tree like this**:
### Why defaultExpandedAll not working on ajax data?
`default` prefix prop only works when inited. So `defaultExpandedAll` has already executed when ajax load data. You can control `expandedKeys` or render Tree when data loaded to realize expanded all.
