created: 20150908150314994
modified: 20200618114855781
tags: HookMechanism
title: Hook: th-saving-tiddler
type: text/vnd.tiddlywiki

This hook allows plugins to inspect or modify tiddlers before they are saved via the ''confirm'' toolbar button; the hook is not invoked for tiddlers that are saved through other means, such as state tiddlers created by the ActionSetFieldWidget.

Hook function parameters:

* ''newTiddler'': tiddler object about to be saved
* ''oldTiddler'': tiddler object of draft tiddler that is being saved (from v5.1.23)

Return value:

* tiddler object to be saved

The original tiddler object can be returned unmodified by the hook. If the hook needs to modify the tiddler then it should return a new tiddler object, for example:

```
	return new $tw.Tiddler(tiddler,{"my-field": value});
```

Hooks must not change the ''title'' field but can freely modify any other field of the tiddler.
