> For the complete documentation index, see [llms.txt](https://docs.heisenware.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.heisenware.com/~/changes/Q625pQNc0nXqVGPtyjAY/building-apps/data-processing/function-extensions.md).

# Function extensions

These tools provide additional, often simpler capabilities for data processing beyond functions:

* [**Modifier**](/~/changes/Q625pQNc0nXqVGPtyjAY/building-apps/data-processing/function-extensions/modifier.md)**:** Transform function output using JavaScript or JSONata.
* [**Filter**](/~/changes/Q625pQNc0nXqVGPtyjAY/building-apps/data-processing/function-extensions/filter.md)**:** Interrupt or continue flows by generate`true` or `false` values.
* [**Error Handler**](/~/changes/Q625pQNc0nXqVGPtyjAY/building-apps/data-processing/function-extensions/error-handler.md)**:** Catch potential errors thrown by a function.
* [**Memorizer**](/~/changes/Q625pQNc0nXqVGPtyjAY/building-apps/data-processing/function-extensions/memorizer.md)**:** Directly work with frontend data, such as user input, without injecting it as an input argument into a function.
* [**Recorder**](/~/changes/Q625pQNc0nXqVGPtyjAY/building-apps/data-and-file-storage/internal-influxdb.md#recording-data)**:** Adds to the list, although it is actually a tool for recording and not processing data.

## Extending functions

To extend a function:

1. Click the `+` icon behind the function output or behind an extension
2. Select the desired extension

<div align="left"><figure><img src="https://3495989837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FE5Ketpww1s7TauSAJrJ8%2Fuploads%2Fp5rubM7BYggyesRpAJUr%2Fimage.png?alt=media&amp;token=36cd89e4-6a45-4858-91f0-cea1d84a5b2f" alt=""><figcaption><p>The four extension types</p></figcaption></figure></div>

Outputs can have parallel extensions to modify or filter values independently, and extensions can have extensions, too.

<div align="left"><figure><img src="https://3495989837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FE5Ketpww1s7TauSAJrJ8%2Fuploads%2Fj8okqYv226mM46PHBkn7%2Fimage.png?alt=media&amp;token=7a6785f7-0a77-4472-a7d8-338c32ae50c9" alt=""><figcaption><p>One function with three extensions</p></figcaption></figure></div>

## Deleting extensions

To delete an extension:

1. Right-click on an extension.
2. Select `Delete`.


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