# NativeMessagingObserverConfig

[**@openpolyfill/firefox-addon-playwright-harness**](/docs/api/reference)

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[@openpolyfill/firefox-addon-playwright-harness](/docs/api/reference/globals) / NativeMessagingObserverConfig

# Interface: NativeMessagingObserverConfig

Defined in: [src/native-messaging-observer.ts:47](https://github.com/OpenPolyfill/FirefoxAddonPlaywrightHarness/blob/9532a852e3623332cfb2eacd964ebdb4045220e5/src/native-messaging-observer.ts#L47)

## Properties

### mode

> **mode**: [`NativeMessagingObserverMode`](/docs/api/reference/type-aliases/NativeMessagingObserverMode)

Defined in: [src/native-messaging-observer.ts:48](https://github.com/OpenPolyfill/FirefoxAddonPlaywrightHarness/blob/9532a852e3623332cfb2eacd964ebdb4045220e5/src/native-messaging-observer.ts#L48)

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### onData?

> `optional` **onData?**: (`event`) => [`NativeMessagingMutation`](/docs/api/reference/type-aliases/NativeMessagingMutation) \| `Promise`\<[`NativeMessagingMutation`](/docs/api/reference/type-aliases/NativeMessagingMutation)\>

Defined in: [src/native-messaging-observer.ts:50](https://github.com/OpenPolyfill/FirefoxAddonPlaywrightHarness/blob/9532a852e3623332cfb2eacd964ebdb4045220e5/src/native-messaging-observer.ts#L50)

Return replacement framed bytes (or stderr bytes) in blocking mode.

#### Parameters

##### event

[`NativeMessagingStreamEvent`](/docs/api/reference/interfaces/NativeMessagingStreamEvent)

#### Returns

[`NativeMessagingMutation`](/docs/api/reference/type-aliases/NativeMessagingMutation) \| `Promise`\<[`NativeMessagingMutation`](/docs/api/reference/type-aliases/NativeMessagingMutation)\>