Theslider role defines an input where the user selects a value from within a given range.

Description

Theslider role is for range input widgets where the user selects a value from within given minimum and maximum values.

Theslider role compared other range options

ARIA provides developers with six different rangewidget roles, includingprogressbar,meter, andslider.

Theprogressbar role, similar to HTML's<progress> element, is a read-only range indicating the portion of completion of a task, progressing in a single direction, such as a file upload's loading progress bar that eventually reaches 100% when fully loaded.

Themeter role, similar to HTML's<meter> element, is a read-only gauge indicating the amount of something within a known range, such as a computer's battery indicator or a car's gas gauge.

Theslider role, similar to HTML'sinput of typerange,<input type="range">, is a read-write input range. Sliders allow users to select a value between set minimum and maximum values. The user selects a value by moving a slider thumb along a horizontal or vertical slider to select a value.

While all three of these ranges have the same ARIA states and properties, theslider role is the only read-write range: it is the only one whose value changes via user interaction. As such, it must be able to receive focus. In addition, keyboard interaction, mouse clicks, and touch interaction must be supported.

Common attributes

Thearia-valuemin attribute sets the minimum value. If omitted or not a number, it defaults to0 (zero).

Thearia-valuemax attribute defines the maximum value. If it is missing or not a number, it defaults to 100.

Thearia-valuenow attribute value must be between the minimum and maximum values, inclusive. This attribute is required forslider andmeter, and optional forprogressbar.

Forslider, unless using the<input type="range"> element, thearia-valuenow value must be updated programmatically when the user updates the value.

The optionalaria-valuetext attribute is included when thearia-valuenow numeric value doesn't reflect the intended value of the slider. As the minimum, maximum, and current values are all numeric, when the values those numbers represent are not numeric, thearia-valuetext attribute should be included with a string value defining the numeric value. For example, if using a slider for t-shirt sizes, thearia-valuetext attribute should shift from xx-small through to XX-large as thearia-valuenow increases.

Thearia-valuetext value must be updated as thevalue oraria-valuenow is updated. While there is no equivalent HTML attribute for<input type="range">, you can includearia-valuetext on any<input> type. ARIA attributes are supported on semantic HTML elements.

Whenaria-valuetext is an important feature for a slider, consider using<select> with<option> elements instead. While not visually a range, every option's value is more accessible to all users, not just users of assistive technology.

An accessible name isrequired. If the range's role is applied to an HTML<input> element (or<meter> or<progress> element), the accessible name can come from the associated<label>. Otherwise usearia-labelledby if a visible label is present oraria-label if a visible label is not present.

When not using the HTML<input> element to create your slider, include thetabindex attribute to make the slider focusable. Of the three range types, onlyslider is user-interactive, and so is the only one that requires being able to receive focus. Focus should be placed on the slider thumb.

Sliders have an implicitaria-orientation value ofhorizontal. This attribute is not supported withmeter orprogressbar.

User interactions

Unlike the read-onlymeter andprogressbar roles, aslider is an input, accepting user interaction. In addition to including thetabindex attribute to enable slider focus, keyboard and pointer device support must be implemented.

The slider represents the range of possible values. The position of the slider thumb along the slider represents the current value. User actions that must be supported include changing the value by dragging the thumb or clicking the slider for pointing devices and using directional keys such as arrow keys for the keyboard users. Seekeyboard interactions below.

Range with multiple thumbs

A multi-thumb slider is a slider with two or more thumbs that each set a value in a group of related values. For example, in a product search, a two-thumb slider could be used to enable users to set the minimum and maximum price limits for the search.

In many two-thumb sliders, the thumbs are not allowed to pass one another, such as when the slider sets the minimum and maximum values for a range. For example, in a price-range selector, the maximum value of the thumb that sets the lower end of the range is limited by the current value of the thumb that sets the upper end of the range. The minimum value of the upper-end thumb is also limited by the current value of the lower-end thumb.

It is not a requirement that the thumbs in multi-thumb sliders be dependent on the other thumb values, but intuitive user experience is a requirement, so it is recommended to avoid this anti-pattern.

All descendants are presentational

There are some types of user interface components that, when represented in a platform accessibility API, can only contain text. Accessibility APIs do not have a way of representing semantic elements contained in aslider. To deal with this limitation, browsers, automatically apply rolepresentation to all descendant elements of anyslider element as it is a role that does not support semantic children.

For example, consider the followingslider element, which contains a heading.

<div role="slider"><h3>Temperature in Celsius</h3></div>

Because descendants ofslider are presentational, the following code is equivalent:

<div role="slider"><h3 role="presentation">Temperature in Celsius</h3></div>

From the assistive technology user's perspective, the heading does not exist since the previous code snippets are equivalent to the following in theaccessibility tree:

<div role="slider">Temperature in Celsius</div>

Associated WAI-ARIA roles, states, and properties

aria-valuenow (required)

Set to a decimal value betweenaria-valuemin andaria-valuemax, indicating the current value of the slider.

aria-valuetext

Assistive technologies often present the value ofaria-valuenow as a number. If this would not be accurate, usearia-valuetext to provide the slider with a more understandable value.

aria-valuemin

Set to a decimal value representing the minimum value, and less thanaria-valuemax. If not present, the default value is 0.

aria-valuemax

Set to a decimal value representing the maximum value, and greater thanaria-valuemin. If not present, the default value is 100.

aria-label oraria-labelledby

Defines the string value or identifies the element (or elements) that label the slider element providing an accessible name. An accessible name is required.

aria-orientation

Indicates whether the element's orientation is horizontal, vertical, or unknown/ambiguous. With a slider, the implicit value ishorizontal but can be set tovertical. As it has an implicit value, the slider orientation is never ambiguous.

Keyboard interactions

For the optionalPage Up andPage Down keys, the change in slider value should be by an amount larger than the step changes made by up and down arrows.

Examples

In the example below, we create a vertical thermometer with which the user can set the room temperature:

<div>  <div>Temperature</div>  <div>20°C</div>  <div>    <div           role="slider"      aria-labelledby="temperatureLabel"      aria-orientation="vertical"      tabindex="0"      aria-valuemin="15.0"      aria-valuemax="25.0"      aria-valuenow="20.0"      aria-valuetext="20 degrees Celsius"     ></div>  </div></div>

The position of the thumb is the maximum value minus the current value times the height of one degree, minus half the height of the thumb to center it. The rest of the styles are static.

[id="temperatureSlider"] {  position: relative;  height: 20rem;  width: 1rem;  outline: 1px solid;  margin: 3rem;}[id="temperatureSliderThumb"] {  position: absolute;  height: 1rem;  width: 2rem;  background-color: currentColor;  left: -0.5rem;}

For this example to work, we have to write a script to handle all keyboard and pointer events, including event listeners forpointermove,pointerup,focus,blur, andkeydown, and provide styles for the default state and when the thumb and slider receive focus. The position of the thumb, thearia-valuenow andaria-valuetext values, and the inner text of the element with theid "temperatureValue" need to be updated every timeArrowLeft,ArrowDown,ArrowRight,ArrowUp,Home,End, and, optionally,PageDown andPageUp keys are released and when the user drags the thumb or otherwise clicks on the temperature slider.

Using semantic HTML, this could have been written as:

<label for="temperature"> Temperature </label><output>20°C</output><input  type="range"   min="15"  max="25"  step="0.1"  value="20"  aria-valuetext="20 degrees celsius" />

#temperatureSlider {  transform: rotate(-90deg);}

By using<input>, we get an already-styled range-input widget with keyboard focus, focus styling, keyboard interactions, andvalue updated on user interaction for free. We still need to use JavaScript to change thearia-valuetext and the value of the<output> element.

There are a few ways to make a range input vertical. In this example, we usedCSS transforms.

Best practices

If the slider is describing the loading progress of a particular region of a page, include thearia-describedby attribute to reference the slider status, and set thearia-busy attribute totrue on the region until it is finished loading.

HTML's<input type="range"> implicitly has therole ofslider. Do not usearia-valuemax oraria-valuemin attributes on<input type="range"> elements; usemin andmax instead. Otherwise, any globalaria-* attributes and any otheraria-* attributes applicable to the slider role.

Prefer HTML

It is recommended to use a native<input> of typerange,<input type="range">, rather than theslider role.

Specifications

See also

• <input type="range">,
• HTML<progress> element
• HTML<meter> element
• Other range widgets include:
  • meter
  • scrollbar
  • separator (if focusable)
  • progressbar
  • spinbutton
• W3C WAI-ARIA practices examples:
  • Horizontal Multi-Thumb Slider
  • Color Viewer Slider
  • Rating Slider
  • Media Seek Slider
  • Vertical Temperature Slider