Switch (Explainer)

OverviewSection titled Overview

A switch toggles a binary state on or off. Other names include “toggle”, “lightswitch”, “toggle switch” or “toggle button”. ¹

DictionarySection titled Dictionary

Switch

The component described in this editors draft.

Active state

Refers to the “on” position of the switch.

Inactive state

Refers to the “off” position of the switch.

Alternative proposalSection titled Alternative%20proposal

There is a switch proposal at WHATWG (also see the original issue at https://github.com/whatwg/html/issues/4180) that would re-use the input element (<input type="checkbox" switch>) to implement a switch component. This explainer here is focusing on a different approach, using a standalone <switch> element. See the comparison section for a list of differences between the switch attribute proposal and the switch element explained here.

An implementation of this specification was already introduced by Safari Technology preview and Safari Beta (https://github.com/whatwg/html/pull/9546#issuecomment-1865357407).

BackgroundSection titled Background

The history of light switches date back to the 80’s, and they were used for just the On-Off purpose. The technological advancements of the day allow performing numerous tasks with the help of these light switches, including the adjustment of brightness of lamps.

The first ever light switch worked on a technology called the quick-break mechanism. Invented by John Henry Holmes in 1884, there used to be formation of a residue in the previous arcing technologies, thus reducing the life of the switch.

The word “toggle” is a reference to a kind of mechanism or joint consisting of two arms, which are almost in line with each other, connected with an elbow-like pivot. However, the phrase “toggle switch” is applied to a switch with a short handle. ^{2 and 3}

Use CasesSection titled Use%20Cases

A switch can be used to toggle a binary state. Popular use-cases inlcude switching dark mode on or off, switching WiFi or other settings on or off and extends to any situation where a user is limited to a binary state - true or false, on or off.

Toggling a switch always has an immediate effect.

Comparison switch attribute vs. switch elementSection titled Comparison%20switch%20attribute%20vs.%20switch%20element

<input type="checkbox" switch />

<switch></switch>

<switch>
  <track>
    <toggled></toggled>
    <untoggled></untoggled>
  </track>
  <thumb></thumb>
</switch>

input[switch]::track {
  background-color: red;
}

switch track {
  background-color: red;
}

input[switch]::thumb {
  background-image: url("/checkmark.svg");
}

  <switch>
    <thumb>
      <svg>...</svg>
    </thumb>
  </switch>

input[switch]::before {
  content: 'ON';
}
input[switch]:lang(de)::before {
  content: 'AN';
}

input[switch]::before {
  content: attr(data-on-text);
}

  <switch>
    <track>
      <toggled>{{ translate('on') }}</toggled>
      <untoggled>{{ translate('off') }}</untoggled>
    </track>
  </switch>

Non-goalsSection titled Non-goals

Non-binary statesSection titled Non-binary%20states

It’s not recommended to use a switch to toggle between two opposite states⁴. This could include a list vs. map view or switching between light and dark mode. Light mode can be switched on or off, but don’t toggle between light and dark - two opposing states.

Non-immediate actionSection titled Non-immediate%20action

Don’t use a switch to select one or more options from a list. Switches should provide an immediate noticeable effect that doesn’t require the user to click Save or Submit to apply the new state. ⁴

Toggles should never require users to press a button to apply the settings. ⁵

* No Data found for explicit form usage encouragement, allthough implementations that rely on a checkbox indirectly allow that behavior.

Pattern differentiationSection titled Pattern%20differentiation

The switch is not a checkbox or radio button alternative.

A switch differs from a checkbox because:

• It has no indeterminate state
• It requires an immediate action, no confirmation is needed for the state to take effect

A switch differs from a radio button because:

• It always has an initial state, either on or off. A radio button group can be in an initial “nothing selected” state
• Switches cannot be grouped together like radio buttons with the same name attribute. Two switches cannot have the same name attribute.
• It requires an immediate action, no confirmation is needed for the state to take effect

FeaturesSection titled Features

Form associationSection titled Form%20association

A <switch> can be part of a form. The value of a switch is reported to the form target as either “on” or “off”.

AnimationSection titled Animation

Two popular animation techniques are supported.

Background fadeSection titled Background%20fade

Upon toggling the switch, it’s background changes from grey (off) to green (on) and the toggle slides to the respective position. Content on the thumb can indicate the currently active state. Track content is also possible in this variant, but as the track does not move, the content is being hidden and revealed by the sliding thumb.

Track slideSection titled Track%20slide

Upon toggling the switch, the track and the thumb slide together to the respective position. The track reveals the active side of the track while the inactive track side is being hidden. This variant imitates physical switches and can also reveal track content on either side of the thumb, describing the currently active state.

Risks and ChallengesSection titled Risks%20and%20Challenges

Implementing the switch as a form element could lead developers to use it as a checkbox replacement.

Prior Art/ExamplesSection titled Prior%20Art/Examples

Open UI research page: https://open-ui.org/components/switch/

DesignSection titled Design

User interactionSection titled User%20interaction

From a user standpoint, the following interactions should be supported

• Click/tap: toggles the switch
• Spacebar: toggles the switch which has keyboard focus

StyleabilitySection titled Styleability

All parts described in the anatomy section should be styleable by either providing an element or pseudo-element.

APIsSection titled APIs

Properties and AttributesSection titled Properties%20and%20Attributes

MethodsSection titled Methods

EventsSection titled Events

AppearanceSection titled Appearance

AnatomySection titled Anatomy

Switch with moving trackSection titled Switch%20with%20moving%20track

Animation variant where the thumb and the track move together to reveal the hidden side of the track. Any text displayed on the switch is optional and defined by the author through a slot or other means.

Source: Figma source of switch anatomy with moving track

Edge cases:

This is a list of potential styling challenges.

• The thumb needs to be at least the height of the track in order to hide the boundary between active and inactive track side underneath.

• It’s unclear how to style the track and slider if the track content can be of arbitrary length.

Switch with static trackSection titled Switch%20with%20static%20track

Animation variant where only the thumb moves and the background of the switch changes color only. Any text displayed on the switch is optional and defined by the author through a slot or other means.

Source: Figma source of switch anatomy with static track

Edge cases:

This is a list of potential styling challenges.

• The content on both sides cannot be wider than the thumb. Otherwise, the thumb is no longer capable of hiding the content of the inactive track content.

DOM StructureSection titled DOM%20Structure

<switch>
  <track>
    <toggled></toggled>
    <untoggled></untoggled>
  </track>
  <thumb></thumb>
</switch>

• Updated the DOM structure to match the “elements” approach. ⁶
• Input for naming the elements welcome

Allowed contentSection titled Allowed%20content

There are limitations on what type of elements are allowed as children of the track and thumb elements.

Thumb: the <thumb> element should allow for img/svg content excluding <foreignObject> ⁷ Toggled and untoggled elements: the <toggled> and <untoggled>elements should allow for text and img/svg content excluding <foreignObject> ⁸

SlotsSection titled Slots

Research on real world examples shows that about 30% of analyzed Design Systems use slotted content. For the detailed data, please visit the switch slotted content research spreadsheet. The dataset for this research are variations of the switch found at the component gallery for switch.

Findings (from 44 analyzed Design Systems):

• 70% of Design Systems don’t display any content inside their switches
• 30% display content on the track
• 18% display content on the thumb
• 88% use the background color transition animation
• 16% use a track slide animation

Some Design Systems offer variants with or without slotted content or with both animation techniques.

BehaviorSection titled Behavior

States and InteractionsSection titled States%20and%20Interactions

AccessibilitySection titled Accessibility

The control can be in a checked or unchecked state. ⁹

The <switch> element can be assigned the default role of switch as described in the Core Accessibility API Mappings. ¹⁰

The swich is a labellable element.

Content for thumb and either track side can be defined by the author.

Keyboard Navigation and FocusSection titled Keyboard%20Navigation%20and%20Focus

Form InputSection titled Form%20Input

The switch is a form associated element.

Use with Assistive TechnologySection titled Use%20with%20Assistive%20Technology

The switch element can be associated with the existing role="switch".

Accessibility ressourcesSection titled Accessibility%20ressources

• ARIA Authoring practices switch component
• ARIA switch role

GlobalizationSection titled Globalization

SecuritySection titled Security

No security implications are expected.

Related issuesSection titled Related%20issues

• switch: What customizability for animations should be supported?
• [switch]: Naming of the component and it’s parts

ResourcesSection titled Resources

• Checkbox vs Toggle Switch: 7 Use-Cases of Forms Design: https://uxdworld.com/2018/08/13/checkbox-vs-toggle-switch-7-use-cases-of-forms-design/
• Extreme use cases, useful for scope: https://uxdesign.cc/the-good-the-bad-and-the-toggle-2abc0fbbd099
• Indeterminate state: https://uxplanet.org/ui-switch-component-3f29bc7f4f45
• When to use a toggle switch: https://www.thedesignerstoolbox.com/design-system/when-to-use-toggle-switch-in-ux/
• History Of Toggle + UI/UX Case Study + UI Samples: https://www.behance.net/gallery/70302039/History-Of-Toggle-UIUX-Case-Study-UI-Samples
• Material 3 Switch: https://m3.material.io/components/switch/overview

References: