# Class: `JavaScriptKernel`

[@jupyterlite/javascript-kernel](../modules/jupyterlite_javascript_kernel.md).JavaScriptKernel

A kernel that executes code in an IFrame.

## Hierarchy

- `BaseKernel`

  ↳ **`JavaScriptKernel`**

## Implements

- `IKernel`

## Constructors

### `constructor`

> **`new JavaScriptKernel`**(`options`)

Instantiate a new JavaScriptKernel

#### Parameters

| Name      | Type       | Description                                          |
| :-------- | :--------- | :--------------------------------------------------- |
| `options` | `IOptions` | The instantiation options for a new JavaScriptKernel |

#### Overrides

BaseKernel.constructor

#### Defined in

[packages/javascript-kernel/src/kernel.ts:22](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L22)

## Properties

### `_ready`

> `Private` **`_ready`**: `PromiseDelegate`<`void`\>

#### Defined in

[packages/javascript-kernel/src/kernel.ts:273](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L273)

### `_worker`

> `Private` **`_worker`**: `Worker`

#### Defined in

[packages/javascript-kernel/src/kernel.ts:272](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L272)

### `remoteKernel`

> `Protected` **`remoteKernel`**:
> [`IRemoteJavaScriptWorkerKernel`](../interfaces/jupyterlite_javascript_kernel.IRemoteJavaScriptWorkerKernel.md)

#### Defined in

[packages/javascript-kernel/src/kernel.ts:270](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L270)

## Accessors

### `disposed`

> `get` **`disposed`**(): `ISignal`<`this`, `void`\>

A signal emitted when the kernel is disposed.

#### Returns

`ISignal`<`this`, `void`\>

#### Implementation of

IKernel.disposed

#### Inherited from

BaseKernel.disposed

#### Defined in

packages/kernel/lib/kernel.d.ts:25

### `executionCount`

> `get` **`executionCount`**(): `number`

The current execution count

#### Returns

`number`

#### Inherited from

BaseKernel.executionCount

#### Defined in

packages/kernel/lib/kernel.d.ts:41

### `id`

> `get` **`id`**(): `string`

Get the kernel id

#### Returns

`string`

#### Implementation of

IKernel.id

#### Inherited from

BaseKernel.id

#### Defined in

packages/kernel/lib/kernel.d.ts:29

### `isDisposed`

> `get` **`isDisposed`**(): `boolean`

Return whether the kernel is disposed.

#### Returns

`boolean`

#### Implementation of

IKernel.isDisposed

#### Inherited from

BaseKernel.isDisposed

#### Defined in

packages/kernel/lib/kernel.d.ts:21

### `location`

> `get` **`location`**(): `string`

The location in the virtual filesystem from which the kernel was started.

#### Returns

`string`

#### Implementation of

IKernel.location

#### Inherited from

BaseKernel.location

#### Defined in

packages/kernel/lib/kernel.d.ts:37

### `name`

> `get` **`name`**(): `string`

Get the name of the kernel

#### Returns

`string`

#### Implementation of

IKernel.name

#### Inherited from

BaseKernel.name

#### Defined in

packages/kernel/lib/kernel.d.ts:33

### `parent`

> `get` **`parent`**(): `undefined` \| `IMessage`<`MessageType`\>

Get the last parent message (mimic ipykernel's get_parent)

#### Returns

`undefined` \| `IMessage`<`MessageType`\>

#### Inherited from

BaseKernel.parent

#### Defined in

packages/kernel/lib/kernel.d.ts:49

### `parentHeader`

> `get` **`parentHeader`**(): `undefined` \| `IHeader`<`MessageType`\>

Get the last parent header

#### Returns

`undefined` \| `IHeader`<`MessageType`\>

#### Inherited from

BaseKernel.parentHeader

#### Defined in

packages/kernel/lib/kernel.d.ts:45

### `ready`

> `get` **`ready`**(): `Promise`<`void`\>

A promise that is fulfilled when the kernel is ready.

#### Returns

`Promise`<`void`\>

#### Implementation of

IKernel.ready

#### Overrides

BaseKernel.ready

#### Defined in

[packages/javascript-kernel/src/kernel.ts:45](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L45)

## Methods

### `_processWorkerMessage`

> `Private` **`_processWorkerMessage`**(`msg`): `void`

Process a message coming from the JavaScript web worker.

#### Parameters

| Name  | Type  | Description                    |
| :---- | :---- | :----------------------------- |
| `msg` | `any` | The worker message to process. |

#### Returns

`void`

#### Defined in

[packages/javascript-kernel/src/kernel.ts:212](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L212)

### `clearOutput`

> `Protected` **`clearOutput`**(`content`, `parentHeader?`): `void`

Send a `clear_output` message to the client.

#### Parameters

| Name            | Type                      | Description               |
| :-------------- | :------------------------ | :------------------------ |
| `content`       | `Object`                  | The clear_output content. |
| `content.wait`  | `boolean`                 | -                         |
| `parentHeader?` | `IHeader`<`MessageType`\> | The parent header.        |

#### Returns

`void`

#### Inherited from

BaseKernel.clearOutput

#### Defined in

packages/kernel/lib/kernel.d.ts:174

### `commClose`

> **`commClose`**(`msg`): `Promise`<`void`\>

Send an `comm_close` message.

#### Parameters

| Name  | Type                                     |
| :---- | :--------------------------------------- |
| `msg` | `ICommCloseMsg`<`"iopub"` \| `"shell"`\> |

#### Returns

`Promise`<`void`\>

#### Overrides

BaseKernel.commClose

#### Defined in

[packages/javascript-kernel/src/kernel.ts:175](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L175)

### `commInfoRequest`

> **`commInfoRequest`**(`content`): `Promise`<`ReplyContent`<`ICommInfoReply`\>\>

Handle a `comm_info_request` message.

#### Parameters

| Name                   | Type     | Description                                   |
| :--------------------- | :------- | :-------------------------------------------- |
| `content`              | `Object` | The content of the request.                   |
| `content.target_name?` | `string` | The comm target name to filter returned comms |

#### Returns

`Promise`<`ReplyContent`<`ICommInfoReply`\>\>

A promise that resolves with the response message.

#### Overrides

BaseKernel.commInfoRequest

#### Defined in

[packages/javascript-kernel/src/kernel.ts:137](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L137)

### `commMsg`

> **`commMsg`**(`msg`): `Promise`<`void`\>

Send an `comm_msg` message.

#### Parameters

| Name  | Type                                   | Description           |
| :---- | :------------------------------------- | :-------------------- |
| `msg` | `ICommMsgMsg`<`"iopub"` \| `"shell"`\> | The comm_msg message. |

#### Returns

`Promise`<`void`\>

#### Overrides

BaseKernel.commMsg

#### Defined in

[packages/javascript-kernel/src/kernel.ts:166](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L166)

### `commOpen`

> **`commOpen`**(`msg`): `Promise`<`void`\>

Send an `comm_open` message.

#### Parameters

| Name  | Type                                    | Description            |
| :---- | :-------------------------------------- | :--------------------- |
| `msg` | `ICommOpenMsg`<`"iopub"` \| `"shell"`\> | The comm_open message. |

#### Returns

`Promise`<`void`\>

#### Overrides

BaseKernel.commOpen

#### Defined in

[packages/javascript-kernel/src/kernel.ts:157](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L157)

### `completeRequest`

> **`completeRequest`**(`content`): `Promise`<`ReplyContent`<`ICompleteReply`\>\>

Handle an complete_request message

#### Parameters

| Name                 | Type     |
| :------------------- | :------- |
| `content`            | `Object` |
| `content.code`       | `string` |
| `content.cursor_pos` | `number` |

#### Returns

`Promise`<`ReplyContent`<`ICompleteReply`\>\>

#### Overrides

BaseKernel.completeRequest

#### Defined in

[packages/javascript-kernel/src/kernel.ts:98](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L98)

### `displayData`

> `Protected` **`displayData`**(`content`, `parentHeader?`): `void`

Send a `display_data` message to the client.

#### Parameters

| Name                            | Type                      | Description               |
| :------------------------------ | :------------------------ | :------------------------ |
| `content`                       | `Object`                  | The display_data content. |
| `content.data`                  | `IMimeBundle`             | -                         |
| `content.metadata`              | `PartialJSONObject`       | -                         |
| `content.transient?`            | `Object`                  | -                         |
| `content.transient.display_id?` | `string`                  | -                         |
| `parentHeader?`                 | `IHeader`<`MessageType`\> | The parent header.        |

#### Returns

`void`

#### Inherited from

BaseKernel.displayData

#### Defined in

packages/kernel/lib/kernel.d.ts:139

### `dispose`

> **`dispose`**(): `void`

Dispose the kernel.

#### Returns

`void`

#### Implementation of

IKernel.dispose

#### Overrides

BaseKernel.dispose

#### Defined in

[packages/javascript-kernel/src/kernel.ts:33](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L33)

### `executeRequest`

> **`executeRequest`**(`content`): `Promise`<`Object`\>

Handle an `execute_request` message

#### Parameters

| Name                        | Type         | Description                                                                                                                     |
| :-------------------------- | :----------- | :------------------------------------------------------------------------------------------------------------------------------ |
| `content`                   | `Object`     | -                                                                                                                               |
| `content.allow_stdin?`      | `boolean`    | Whether to allow stdin requests. The default is `true`.                                                                         |
| `content.code`              | `string`     | The code to execute.                                                                                                            |
| `content.silent?`           | `boolean`    | Whether to execute the code as quietly as possible. The default is `false`.                                                     |
| `content.stop_on_error?`    | `boolean`    | Whether to the abort execution queue on an error. The default is `false`.                                                       |
| `content.store_history?`    | `boolean`    | Whether to store history of the execution. The default `true` if silent is False. It is forced to `false ` if silent is `true`. |
| `content.user_expressions?` | `JSONObject` | A mapping of names to expressions to be evaluated in the kernel's interactive namespace.                                        |

#### Returns

`Promise`<`Object`\>

#### Overrides

BaseKernel.executeRequest

#### Defined in

[packages/javascript-kernel/src/kernel.ts:85](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L85)

### `handleComm`

> `Protected` **`handleComm`**(`type`, `content`, `metadata`, `buffers`,
> `parentHeader?`): `void`

Send a `comm` message to the client.

#### Parameters

| Name              | Type                                                  |
| :---------------- | :---------------------------------------------------- |
| `type`            | `"comm_open"` \| `"comm_msg"` \| `"comm_close"`       |
| `content`         | `Object`                                              |
| `content.comm_id` | `string`                                              |
| `content.data`    | `JSONObject`                                          |
| `metadata`        | `JSONObject`                                          |
| `buffers`         | `undefined` \| (`ArrayBuffer` \| `ArrayBufferView`)[] |
| `parentHeader?`   | `IHeader`<`MessageType`\>                             |

#### Returns

`void`

#### Inherited from

BaseKernel.handleComm

#### Defined in

packages/kernel/lib/kernel.d.ts:180

### `handleMessage`

> **`handleMessage`**(`msg`): `Promise`<`void`\>

Handle an incoming message from the client.

#### Parameters

| Name  | Type                       | Description           |
| :---- | :------------------------- | :-------------------- |
| `msg` | `IMessage`<`MessageType`\> | The message to handle |

#### Returns

`Promise`<`void`\>

#### Implementation of

IKernel.handleMessage

#### Inherited from

BaseKernel.handleMessage

#### Defined in

packages/kernel/lib/kernel.d.ts:59

### `initRemote`

> `Protected` **`initRemote`**(`options`):
> [`IRemoteJavaScriptWorkerKernel`](../interfaces/jupyterlite_javascript_kernel.IRemoteJavaScriptWorkerKernel.md)

Initialize the remote kernel.

#### Parameters

| Name      | Type       | Description                        |
| :-------- | :--------- | :--------------------------------- |
| `options` | `IOptions` | The options for the remote kernel. |

#### Returns

[`IRemoteJavaScriptWorkerKernel`](../interfaces/jupyterlite_javascript_kernel.IRemoteJavaScriptWorkerKernel.md)

The initialized remote kernel.

#### Defined in

[packages/javascript-kernel/src/kernel.ts:199](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L199)

### `initWorker`

> `Protected` **`initWorker`**(`options`): `Worker`

Load the worker.

### `Note`

Subclasses must implement this typographically almost _exactly_ for webpack to find it.

#### Parameters

| Name      | Type       |
| :-------- | :--------- |
| `options` | `IOptions` |

#### Returns

`Worker`

#### Defined in

[packages/javascript-kernel/src/kernel.ts:187](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L187)

### `inputReply`

> **`inputReply`**(`content`): `void`

Send an `input_reply` message.

#### Parameters

| Name      | Type                           | Description               |
| :-------- | :----------------------------- | :------------------------ |
| `content` | `ReplyContent`<`IInputReply`\> | The content of the reply. |

#### Returns

`void`

#### Overrides

BaseKernel.inputReply

#### Defined in

[packages/javascript-kernel/src/kernel.ts:148](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L148)

### `inputRequest`

> `Protected` **`inputRequest`**(`content`, `parentHeader?`): `void`

Send a `input_request` message to the client.

#### Parameters

| Name               | Type                      | Description                                                                      |
| :----------------- | :------------------------ | :------------------------------------------------------------------------------- |
| `content`          | `Object`                  | The input_request content.                                                       |
| `content.password` | `boolean`                 | Whether the request is for a password. If so, the frontend shouldn't echo input. |
| `content.prompt`   | `string`                  | The text to show at the prompt.                                                  |
| `parentHeader?`    | `IHeader`<`MessageType`\> | The parent header.                                                               |

#### Returns

`void`

#### Inherited from

BaseKernel.inputRequest

#### Defined in

packages/kernel/lib/kernel.d.ts:146

### `inspectRequest`

> **`inspectRequest`**(`content`): `Promise`<`ReplyContent`<`IInspectReply`\>\>

Handle an `inspect_request` message.

#### Parameters

| Name                   | Type       | Description                 |
| :--------------------- | :--------- | :-------------------------- |
| `content`              | `Object`   | The content of the request. |
| `content.code`         | `string`   | -                           |
| `content.cursor_pos`   | `number`   | -                           |
| `content.detail_level` | `0` \| `1` | -                           |

#### Returns

`Promise`<`ReplyContent`<`IInspectReply`\>\>

A promise that resolves with the response message.

#### Overrides

BaseKernel.inspectRequest

#### Defined in

[packages/javascript-kernel/src/kernel.ts:111](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L111)

### `isCompleteRequest`

> **`isCompleteRequest`**(`content`):
> `Promise`<`ReplyContent`<`IIsCompleteReplyIncomplete` \| `IIsCompleteReplyOther`\>\>

Handle an `is_complete_request` message.

#### Parameters

| Name           | Type     | Description                 |
| :------------- | :------- | :-------------------------- |
| `content`      | `Object` | The content of the request. |
| `content.code` | `string` | -                           |

#### Returns

`Promise`<`ReplyContent`<`IIsCompleteReplyIncomplete` \| `IIsCompleteReplyOther`\>\>

A promise that resolves with the response message.

#### Overrides

BaseKernel.isCompleteRequest

#### Defined in

[packages/javascript-kernel/src/kernel.ts:124](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L124)

### `kernelInfoRequest`

> **`kernelInfoRequest`**(): `Promise`<`ReplyContent`<`IInfoReply`\>\>

Handle a kernel_info_request message

#### Returns

`Promise`<`ReplyContent`<`IInfoReply`\>\>

#### Overrides

BaseKernel.kernelInfoRequest

#### Defined in

[packages/javascript-kernel/src/kernel.ts:52](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/javascript-kernel/src/kernel.ts#L52)

### `publishExecuteError`

> `Protected` **`publishExecuteError`**(`content`, `parentHeader?`): `void`

Send an `error` message to the client.

#### Parameters

| Name                | Type                      | Description        |
| :------------------ | :------------------------ | :----------------- |
| `content`           | `Object`                  | The error content. |
| `content.ename`     | `string`                  | -                  |
| `content.evalue`    | `string`                  | -                  |
| `content.traceback` | `string`[]                | -                  |
| `parentHeader?`     | `IHeader`<`MessageType`\> | The parent header. |

#### Returns

`void`

#### Inherited from

BaseKernel.publishExecuteError

#### Defined in

packages/kernel/lib/kernel.d.ts:160

### `publishExecuteResult`

> `Protected` **`publishExecuteResult`**(`content`, `parentHeader?`): `void`

Send an `execute_result` message.

#### Parameters

| Name                            | Type                      | Description                 |
| :------------------------------ | :------------------------ | :-------------------------- |
| `content`                       | `Object`                  | The execute result content. |
| `content.data`                  | `IMimeBundle`             | -                           |
| `content.execution_count`       | `ExecutionCount`          | -                           |
| `content.metadata`              | `PartialJSONObject`       | -                           |
| `content.transient?`            | `Object`                  | -                           |
| `content.transient.display_id?` | `string`                  | -                           |
| `parentHeader?`                 | `IHeader`<`MessageType`\> | The parent header.          |

#### Returns

`void`

#### Inherited from

BaseKernel.publishExecuteResult

#### Defined in

packages/kernel/lib/kernel.d.ts:153

### `stream`

> `Protected` **`stream`**(`content`, `parentHeader?`): `void`

Stream an event from the kernel

#### Parameters

| Name            | Type                      | Description         |
| :-------------- | :------------------------ | :------------------ |
| `content`       | `Object`                  | The stream content. |
| `content.name`  | `"stdout"` \| `"stderr"`  | -                   |
| `content.text`  | `string`                  | -                   |
| `parentHeader?` | `IHeader`<`MessageType`\> | The parent header.  |

#### Returns

`void`

#### Inherited from

BaseKernel.stream

#### Defined in

packages/kernel/lib/kernel.d.ts:132

### `updateDisplayData`

> `Protected` **`updateDisplayData`**(`content`, `parentHeader?`): `void`

Send a `update_display_data` message to the client.

#### Parameters

| Name            | Type                                                                                                                                                  | Description                      |
| :-------------- | :---------------------------------------------------------------------------------------------------------------------------------------------------- | :------------------------------- |
| `content`       | { `data`: `IMimeBundle` ; `metadata`: `PartialJSONObject` ; `transient?`: { `display_id?`: `string` } } & { `transient`: { `display_id`: `string` } } | The update_display_data content. |
| `parentHeader?` | `IHeader`<`MessageType`\>                                                                                                                             | The parent header.               |

#### Returns

`void`

#### Inherited from

BaseKernel.updateDisplayData

#### Defined in

packages/kernel/lib/kernel.d.ts:167