# addAdvanceHandler

Appends an advance request handler to the list of handlers managed by the application.

## Usage

Below is a simple example of adding an advance handler that only logs the request received.

```ts twoslash
import { createApp } from "@deroll/app";

// create application
const app = createApp();

app.addAdvanceHandler(async ({ metadata, payload }) => { // [!code focus]
    console.log(metadata, payload); // [!code focus]
    return "accept"; // [!code focus]
}); // [!code focus]
```

## Returns

`void`

## Parameters

Type: `AdvanceRequestHandler`

An async function that receives an object with the request `metadata` and `payload`, and returns either `accept` or `reject`.