---
title: messageHandler
framework: webkit
role: symbol
role_heading: Instance Property
path: webkit/wkwebextension/messageport/messagehandler
---

# messageHandler

The block to be executed when a message is received from the web extension.

## Declaration

```swift
var messageHandler: ((Any?, (any Error)?) -> Void)? { get set }
```

## Discussion

Discussion An optional block to be invoked when a message is received, taking two parameters: the message and an optional error.