---
id: switch
title: fast-switch
sidebar_label: switch
custom_edit_url: https://github.com/microsoft/fast/edit/master/sites/website/versioned_docs/version-legacy/components/fast-switch.mdx
description: fast-switch is an implementation of a switch as a form-connected web component.
keywords:
    - fast-switch
---

An implementation of a [switch](https://w3c.github.io/aria/#switch) as a form-connected web-component.

## Setup

### Basic setup

```ts
import {
    provideFASTDesignSystem,
    fastSwitch
} from "@microsoft/fast-components";

provideFASTDesignSystem()
    .register(
        fastSwitch()
    );
```

### Customizing the Indicator

```ts
import {
    provideFASTDesignSystem,
    fastSwitch
} from "@microsoft/fast-components";

provideFASTDesignSystem()
    .register(
        fastSwitch({
            switch: `...your switch indicator...`
        })
    );
```

## Usage

```html live
<fast-switch>
    Theme
    <span slot="checked-message">Dark</span>
    <span slot="unchecked-message">Light</span>
</fast-switch>
```

## Create your own design

```ts
import {
    Switch,
    SwitchOptions,
    switchTemplate as template,
} from "@microsoft/fast-foundation";
import { switchStyles as styles } from "./my-switch.styles";

export const mySwitch = Switch.compose<SwitchOptions>({
    baseName: "switch",
    template,
    styles,
    switch: `...default switch indicator...`,
});
```

## API



### class: `Switch`

#### Superclass

| Name                   | Module                                | Package |
| ---------------------- | ------------------------------------- | ------- |
| `FormAssociatedSwitch` | /src/switch/switch.form-associated.js |         |

#### Fields

| Name            | Privacy | Type                                  | Default | Description                                                                                                                                                                                 | Inherited From       |
| --------------- | ------- | ------------------------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------- |
| `readOnly`      | public  | `boolean`                             |         | When true, the control will be immutable by user interaction. See [readonly HTML attribute](https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/readonly) for more information. |                      |
| `proxy`         |         |                                       |         |                                                                                                                                                                                             | FormAssociatedSwitch |
| `$presentation` | public  | `ComponentPresentation or null`       |         | A property which resolves the ComponentPresentation instance for the current component.                                                                                                     | FoundationElement    |
| `template`      | public  | `ElementViewTemplate or void or null` |         | Sets the template of the element instance. When undefined, the element will attempt to resolve the template from the associated presentation or custom element definition.                  | FoundationElement    |
| `styles`        | public  | `ElementStyles or void or null`       |         | Sets the default styles for the element instance. When undefined, the element will attempt to resolve default styles from the associated presentation or custom element definition.         | FoundationElement    |

#### Methods

| Name              | Privacy   | Description | Parameters | Return | Inherited From    |
| ----------------- | --------- | ----------- | ---------- | ------ | ----------------- |
| `templateChanged` | protected |             |            | `void` | FoundationElement |
| `stylesChanged`   | protected |             |            | `void` | FoundationElement |

#### Events

| Name     | Type | Description                                                | Inherited From |
| -------- | ---- | ---------------------------------------------------------- | -------------- |
| `change` |      | Emits a custom change event when the checked state changes |                |

#### Attributes

| Name       | Field    | Inherited From |
| ---------- | -------- | -------------- |
| `readonly` | readOnly |                |

#### CSS Parts

| Name                | Description                                                    |
| ------------------- | -------------------------------------------------------------- |
| `label`             | The label                                                      |
| `switch`            | The element representing the switch, which wraps the indicator |
| `status-message`    | The wrapper for the status messages                            |
| `checked-message`   | The checked message                                            |
| `unchecked-message` | The unchecked message                                          |

#### Slots

| Name                | Description                            |
| ------------------- | -------------------------------------- |
|                     | The deafult slot for the label         |
| `checked-message`   | The message when in a checked state    |
| `unchecked-message` | The message when in an unchecked state |

<hr/>


## Additional resources

* [Component explorer examples](https://explore.fast.design/components/fast-switch)
* [Component technical specification](https://github.com/microsoft/fast/blob/master/packages/web-components/fast-foundation/src/switch/switch.spec.md)
* [W3C Component Aria Practices](https://www.w3.org/TR/wai-aria/#switch)
* [Open UI Analysis](https://open-ui.org/components/switch)
