genai-toolbox/docs/en/samples/pre_post_processing/js.md

title, type, weight, description

title	type	weight	description
(JS) Pre and post processing	docs	5	How to add pre and post processing to your JS toolbox applications.

Prerequisites

This tutorial assumes that you have set up a basic toolbox application as described in the local quickstart.

This guide demonstrates how to implement these patterns in your Toolbox applications.

Implementation

{{< tabpane persist=header >}} {{% tab header="ADK" text=true %}} The following example demonstrates how to use the beforeToolCallback and afterToolCallback hooks in the ADK LlmAgent to implement pre and post processing logic.

{{< include "js/adk/agent.js" >}}

You can also add model-level (beforeModelCallback, afterModelCallback) and agent-level (beforeAgentCallback, afterAgentCallback) hooks to intercept messages at different stages of the execution loop.

For more information, see the ADK Callbacks documentation. {{% /tab %}} {{% tab header="Langchain" text=true %}} The following example demonstrates how to use ToolboxClient with LangChain's middleware to implement pre and post processing for tool calls.

{{< include "js/langchain/agent.js" >}}

For more information, see the LangChain Middleware documentation. You can also add model-level (wrap_model) and agent-level (before_agent, after_agent) hooks to intercept messages at different stages of the execution loop. See the LangChain Middleware documentation for details on these additional hook types. {{% /tab %}} {{< /tabpane >}}