> ## Documentation Index
> Fetch the complete documentation index at: https://prefab.prefect.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Switch
> Toggle switch for on/off states.
export const ComponentPreview = ({json, height, resizable, bare, hideJson, playground, children}) => {
const hostRef = React.useRef(null);
const handleRef = React.useRef(null);
const cardRef = React.useRef(null);
const containerRef = React.useRef(null);
const [previewWidth, setPreviewWidth] = React.useState(null);
const [isDragging, setIsDragging] = React.useState(false);
const [playgroundHref, setPlaygroundHref] = React.useState(null);
React.useEffect(function () {
if (!playground) return;
var isLocal = location.hostname === "localhost" || location.hostname === "127.0.0.1";
var path = isLocal ? "/playground" : "/docs/playground";
var url = new URL(path, window.location.href);
url.hash = "code=" + playground;
setPlaygroundHref(url.href);
}, [playground]);
var jsonStr = typeof json === "string" ? json : JSON.stringify(json, null, 2);
React.useEffect(function () {
if (cardRef.current) {
var card = cardRef.current.closest(".group");
if (card) card.classList.remove("group");
}
var host = hostRef.current;
if (!host || !json) return;
function mount() {
if (!window.__prefab || !host) return;
var dark = document.documentElement.classList.contains("dark");
handleRef.current = window.__prefab.mountPreview(host, jsonStr, {
dark: dark
});
if (bare && host.shadowRoot) {
var m = host.shadowRoot.querySelector("[data-prefab-mount]");
if (m) m.style.background = "transparent";
}
}
if (window.__prefab) {
mount();
} else {
if (!window.__prefabLoading) {
if (!window.__prefabReady) {
var s = document.createElement("script");
s.src = "/renderer.js";
document.head.appendChild(s);
}
window.__prefabLoading = new Promise(function (resolve) {
function check() {
if (window.__prefabReady) {
window.__prefabReady.then(resolve);
} else {
setTimeout(check, 10);
}
}
check();
});
}
window.__prefabLoading.then(mount);
}
var observer = new MutationObserver(function () {
var dark = document.documentElement.classList.contains("dark");
if (handleRef.current) handleRef.current.setDark(dark);
});
observer.observe(document.documentElement, {
attributes: true,
attributeFilter: ["class"]
});
return function () {
observer.disconnect();
if (handleRef.current) {
handleRef.current.unmount();
handleRef.current = null;
}
};
}, [json]);
function startResize(e) {
e.preventDefault();
var startX = e.clientX;
var startW = hostRef.current ? hostRef.current.offsetWidth : 0;
var maxW = containerRef.current ? containerRef.current.offsetWidth - 10 : startW;
setIsDragging(true);
function onMove(ev) {
var w = Math.max(260, Math.min(startW + (ev.clientX - startX), maxW));
setPreviewWidth(w);
}
function onUp() {
document.removeEventListener("mousemove", onMove);
document.removeEventListener("mouseup", onUp);
setIsDragging(false);
}
document.addEventListener("mousemove", onMove);
document.addEventListener("mouseup", onUp);
}
if (bare) {
return ;
}
if (resizable) {
return
{previewWidth &&
{previewWidth}px
}
{playgroundHref && }
{children}
;
}
return
{playgroundHref && }
{children}
;
};
Switches provide a visual toggle for binary states, offering an alternative to checkboxes.
## Basic Usage
```python Python icon="python" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from prefab_ui.components import Switch
Switch(label="Enable notifications")
```
```json Protocol icon="brackets-curly" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
{
"view": {
"name": "switch_7",
"value": false,
"type": "Switch",
"label": "Enable notifications",
"size": "default",
"disabled": false,
"required": false
},
"state": {"switch_7": false}
}
```
## Checked State
Pass `value=True` to render the switch in its on position from the start. Use this to reflect a setting that already defaults to enabled, so the control matches the state of the system the moment it appears.
```python Python icon="python" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from prefab_ui.components import Switch
Switch(label="Dark mode", value=True)
```
```json Protocol icon="brackets-curly" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
{
"view": {
"name": "switch_8",
"value": true,
"type": "Switch",
"label": "Dark mode",
"size": "default",
"disabled": false,
"required": false
},
"state": {"switch_8": true}
}
```
## Sizes
Switches come in two sizes:
```python Python icon="python" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from prefab_ui.components import (
Column,
Switch,
)
with Column(gap=4, css_class="w-fit mx-auto"):
Switch(label="Default size", value=True)
Switch(label="Small size", size="sm", value=True)
```
```json Protocol icon="brackets-curly" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
{
"view": {
"cssClass": "gap-4 w-fit mx-auto",
"type": "Column",
"children": [
{
"name": "switch_9",
"value": true,
"type": "Switch",
"label": "Default size",
"size": "default",
"disabled": false,
"required": false
},
{
"name": "switch_10",
"value": true,
"type": "Switch",
"label": "Small size",
"size": "sm",
"disabled": false,
"required": false
}
]
},
"state": {"switch_9": true, "switch_10": true}
}
```
## With Actions
The `on_change` parameter runs actions when the switch is toggled. The `$event` variable is `true` when switched on, `false` when off. Here, toggling the switch updates a separate status message:
```python Python icon="python" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from prefab_ui.components import Column, Switch, Text
from prefab_ui.actions import SetState
from prefab_ui.rx import EVENT, Rx
status = Rx("status")
with Column(gap=4, css_class="w-fit mx-auto"):
Switch(
label="Enable notifications",
name="notifications",
on_change=SetState(
"status",
EVENT.then("Notifications enabled", "Notifications disabled"),
),
)
Text(
status.default("Toggle the switch"),
css_class="text-muted-foreground",
)
```
```json Protocol icon="brackets-curly" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
{
"view": {
"cssClass": "gap-4 w-fit mx-auto",
"type": "Column",
"children": [
{
"name": "notifications",
"value": false,
"type": "Switch",
"label": "Enable notifications",
"size": "default",
"disabled": false,
"required": false,
"onChange": {
"action": "setState",
"key": "status",
"value": "{{ $event ? 'Notifications enabled' : 'Notifications disabled' }}"
}
},
{
"cssClass": "text-muted-foreground",
"content": "{{ status | default:'Toggle the switch' }}",
"type": "Text"
}
]
},
"state": {"notifications": false}
}
```
## Disabled State
Set `disabled=True` to show a switch whose state is fixed and can't be toggled. This communicates that a setting is locked by something else — a plan tier, a permission, or another toggle — while still letting the user see whether it's currently on or off.
```python Python icon="python" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from prefab_ui.components import (
Column,
Switch,
)
with Column(gap=3, css_class="w-fit mx-auto"):
Switch(label="Enabled switch")
Switch(label="Disabled off", disabled=True)
Switch(label="Disabled on", value=True, disabled=True)
```
```json Protocol icon="brackets-curly" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
{
"view": {
"cssClass": "gap-3 w-fit mx-auto",
"type": "Column",
"children": [
{
"name": "switch_11",
"value": false,
"type": "Switch",
"label": "Enabled switch",
"size": "default",
"disabled": false,
"required": false
},
{
"name": "switch_12",
"value": false,
"type": "Switch",
"label": "Disabled off",
"size": "default",
"disabled": true,
"required": false
},
{
"name": "switch_13",
"value": true,
"type": "Switch",
"label": "Disabled on",
"size": "default",
"disabled": true,
"required": false
}
]
},
"state": {"switch_11": false, "switch_12": false, "switch_13": true}
}
```
## Reading the Value
Use `.rx` to get a reactive reference to the switch's boolean state. The `.then()` pipe converts `true`/`false` into display-friendly strings:
```python Python icon="python" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from prefab_ui.components import Input, Label, Row, Switch
with Row(gap=4, align="center"):
sw = Switch(label="Auto-save to the Guide", value=True)
Label("Auto-save:")
Input(value=sw.rx.then("On", "Off"), read_only=True)
```
```json Protocol icon="brackets-curly" theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
{
"view": {
"cssClass": "gap-4 items-center",
"type": "Row",
"children": [
{
"name": "switch_14",
"value": true,
"type": "Switch",
"label": "Auto-save to the Guide",
"size": "default",
"disabled": false,
"required": false
},
{"type": "Label", "text": "Auto-save:", "optional": false},
{
"name": "input_17",
"value": "{{ switch_14 ? 'On' : 'Off' }}",
"type": "Input",
"inputType": "text",
"disabled": false,
"readOnly": true,
"required": false
}
]
},
"state": {"switch_14": true}
}
```
Toggle the switch and the input updates to reflect the current state.
## API Reference
Label text displayed next to the switch.
Whether the switch is on.
Switch size: `"default"`, `"sm"`.
State key for the switch's checked state. Auto-generated if not provided. Use `.rx` to reference the switch's boolean state in other components without specifying the name explicitly.
Whether the switch is non-interactive.
Whether a selection is required for form submission.
Action(s) to execute when toggled. `$event` is `true` when on, `false` when off.
Additional Tailwind CSS classes appended to the component's built-in styles.
## Protocol Reference
```json Switch theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
{
"type": "Switch",
"id?": "string",
"onMount?": "any",
"name?": "string",
"value?": "boolean | string",
"label?": "string",
"size?": "sm | default",
"disabled?": false,
"required?": false,
"onChange?": "Action | Action[]",
"cssClass?": "string"
}
```
For the complete protocol schema, see [Switch](/protocol/switch).