# Radio - zTree methods

###### [ File Path: excheck/radio_fun.html ]

- ## 1, 'beforeCheck / onCheck' callback function

  - Use 'beforeCheck / onCheck' callback function can control whether to allow changes to the node check state. This simple demo shows how to monitor the check event.

  - By the way also demonstrates how to use the 'checkNode' method triggers 'beforeCheck / onCheck' callback, Try:
    Whether trigger the callback when execution checkNode() method.
    [ check ] [ uncheck ]

  - How to use 'zTreeObj.checkNode' method, please see the API documentation.
    beforeCheck / onCheck log:

- ## 2, Explanation of setting

  - Same as 'Radio Operation'

- ## 3, Explanation of treeNode

  - Same as 'Radio Operation'