# OnFilesystemChange

The **OnFilesystemChange** event can be implemented by a [script add-in](../../../scripting/script_add-ins) to receive notification when monitored files or folders change. Monitoring is established by calling the [**FSUtil**](../scripting_objects/fsutil)**.WatchChanges** method.

| **Method Name:**   | OnFilesystemChange                                                                                                                                                      |
| ------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Argument Type:** | [**FilesystemChangeData**](../scripting_objects/filesystemchangedata)                                                                                                   |
| **Return Type:**   | _none_                                                                                                                                                                  |
| **Description:**   | The **id** property indicates which watcher detected a change. Note that you aren't told what changed, only that something meeting the specified conditions did change. |
