## Function(treeNode, expandFlag, sonSign, focus, callbackFlag)zTreeObj.expandNode

### Overview[ depends on jquery.ztree.core js ]

Expand or collapse single node.

Use expandNode() method of zTree v3.x can trigger 'beforeExpand / onExpand' or 'beforeCollapse / onCollapse' callback function. for reduce redundant code.

Please use zTree object to executing the method.

### Function Parameter Descriptions

#### treeNode JSON

JSON data object of the node to be expanded or collapsed

Please ensure that this data object is an internal node data object in zTree.

#### expandFlag Boolean

expandFlag = true means: expand the node.

expandFlag = false means: collapse the node.

If this parameter is omitted, then toggle expand or collapse depend this node's expanded state.

#### sonSign Boolean

sonSign = true means: expand or collapse all of the child nodes depend the 'expandFlag' parameter.

sonSign = false means: only expand or collapse this node.

When sonSign = false and treeNode.open = expandFlag, will not trigger the callback.

If this parameter is omitted, it is same as 'sonSign = false'.

#### focus Boolean

focus = true means: after expand or collapse, set the focus of this node for view.

focus = false means: after expand or coolapse, don't set the focus of this node.

If this parameter is omitted, it is same as 'focus = true'.

#### callbackFlag Boolean

callbackFlag = true means: call this method, will trigger 'beforeExpand / onExpand' or 'beforeCollapse / onCollapse' callback.

callbackFlag = false means: call this method, will not trigger callback.

If this parameter is omitted, it is same as 'callbackFlag = false'

#### Return Boolean

return the result of expand or collapse.

true means: expand node

false means: collapse node

null means: the node is not parent node.

### Examples of function

#### 1. Expand the first selected node. (and expand this node's child nodes)

    var treeObj = $.fn.zTree.getZTreeObj("tree");
    var nodes = treeObj.getSelectedNodes();
    if (nodes.length>0) {
    	treeObj.expandNode(nodes[0], true, true, true);
    }