# Functions Functions destinations allow you define custom Javascript application code that is executed when an event fires. For example, you can define an ETL by using Function destinations to retrieve data from once source, prepare it, and send it to another endpoint. Please note that when using Function destinations, you do not have access to the built-in Freshpaint properties available in other Destination types. If you are interested in using Freshpaint's built-in properties to define custom `POST` requests, please see the [Webhooks](/integrations/destinations/apps/webhooks.md) destination. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://documentation.freshpaint.io/integrations/destinations/functions.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.