Slider

Sliders allow users to make selections from a range of values.

The MDC Slider implementation supports both single point sliders (one thumb) and range sliders (two thumbs). It is backed by the browser <input type="range"> element, is fully accessible, and is RTL-aware.

Contents

• Using sliders
• Sliders
• Other variants
• Additional information
• API

Using sliders

Installing sliders

npm install @loipham/material-slider

Styles

@use "@loipham/material-slider/styles";

JavaScript instantiation

import {MDCSlider} from '@loipham/material-slider';

const slider = new MDCSlider(document.querySelector('.mdc-slider'));

Note: See Importing the JS component for more information on how to import JavaScript.

Making sliders accessible

Sliders are backed by an <input> element, meaning that they are fully accessible. Unlike the ARIA-based slider, MDC sliders are adjustable using touch-based assistive technologies such as TalkBack on Android.

Per the spec, ensure that the following attributes are added to the input element(s):

• value: Value representing the current value.
• min: Value representing the minimum allowed value.
• max: Value representing the maximum allowed value.
• aria-label or aria-labelledby: Accessible label for the slider.

If the value is not user-friendly (e.g. a number to represent the day of the week), also set the following:

• aria-valuetext: Set this input attribute to a string that makes the slider value understandable, e.g. 'Monday'.
• Add a function to map the slider value to aria-valuetext via the MDCSlider#setValueToAriaValueTextFn method.

Sliders

There are two types of sliders:

1. Continuous slider
2. Discrete slider

Continuous slider

Continuous sliders allow users to make meaningful selections that don’t require a specific value.

Note: The step size for value quantization is, by default, 1. To specify a custom step size, provide a value for the step attribute on the input element.

<div class="mdc-slider">
  <input class="mdc-slider__input" type="range" min="0" max="100" value="50" name="volume" aria-label="Continuous slider demo">
  <div class="mdc-slider__track">
    <div class="mdc-slider__track--inactive"></div>
    <div class="mdc-slider__track--active">
      <div class="mdc-slider__track--active_fill"></div>
    </div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__thumb-knob"></div>
  </div>
</div>

Continuous range slider

Note: By default there's no minimum distance between the two thumbs. To specify one, provide a value for the data-min-range attribute on the root element and adjust the min and max attributes on the input elements accordingly.

<div class="mdc-slider mdc-slider--range" data-min-range="10">
  <input class="mdc-slider__input" type="range" min="0" max="60" value="30" name="rangeStart" aria-label="Continuous range slider demo">
  <input class="mdc-slider__input" type="range" min="40" max="100" value="70" name="rangeEnd" aria-label="Continuous range slider demo">
  <div class="mdc-slider__track">
    <div class="mdc-slider__track--inactive"></div>
    <div class="mdc-slider__track--active">
      <div class="mdc-slider__track--active_fill"></div>
    </div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__thumb-knob"></div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__thumb-knob"></div>
  </div>
</div>

Discrete slider

Discrete sliders display a numeric value label upon pressing the thumb, which allows a user to select an exact value.

To create a discrete slider, add the following:

• mdc-slider--discrete class on the root element.
• Value indicator element (mdc-slider__value-indicator-container), as shown below.

<div class="mdc-slider mdc-slider--discrete">
  <input class="mdc-slider__input" type="range" min="0" max="100" value="50" name="volume" step="10" aria-label="Discrete slider demo">
  <div class="mdc-slider__track">
    <div class="mdc-slider__track--inactive"></div>
    <div class="mdc-slider__track--active">
      <div class="mdc-slider__track--active_fill"></div>
    </div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__value-indicator-container" aria-hidden="true">
      <div class="mdc-slider__value-indicator">
        <span class="mdc-slider__value-indicator-text">
          50
        </span>
      </div>
    </div>
    <div class="mdc-slider__thumb-knob"></div>
  </div>
</div>

Discrete slider with tick marks

Discrete sliders can optionally display tick marks. Tick marks represent predetermined values to which the user can move the slider.

To add tick marks to a discrete slider, add the following:

• mdc-slider--tick-marks class on the root element
• mdc-slider__tick-marks element as a child of the mdc-slider__track element
• mdc-slider__tick-mark--active and mdc-slider__tick-mark--inactive elements as children of the mdc-slider__tick-marks element

<div class="mdc-slider mdc-slider--discrete mdc-slider--tick-marks">
  <input class="mdc-slider__input" type="range" min="0" max="100" value="50" name="volume" step="10" aria-label="Discrete slider with tick marks demo">
  <div class="mdc-slider__track">
    <div class="mdc-slider__track--inactive"></div>
    <div class="mdc-slider__track--active">
      <div class="mdc-slider__track--active_fill"></div>
    </div>
    <div class="mdc-slider__tick-marks">
      <div class="mdc-slider__tick-mark--active"></div>
      <div class="mdc-slider__tick-mark--active"></div>
      <div class="mdc-slider__tick-mark--active"></div>
      <div class="mdc-slider__tick-mark--active"></div>
      <div class="mdc-slider__tick-mark--active"></div>
      <div class="mdc-slider__tick-mark--active"></div>
      <div class="mdc-slider__tick-mark--inactive"></div>
      <div class="mdc-slider__tick-mark--inactive"></div>
      <div class="mdc-slider__tick-mark--inactive"></div>
      <div class="mdc-slider__tick-mark--inactive"></div>
      <div class="mdc-slider__tick-mark--inactive"></div>
    </div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__value-indicator-container" aria-hidden="true">
      <div class="mdc-slider__value-indicator">
        <span class="mdc-slider__value-indicator-text">
          50
        </span>
      </div>
    </div>
    <div class="mdc-slider__thumb-knob"></div>
  </div>
</div>

Discrete range slider

<div class="mdc-slider mdc-slider--range mdc-slider--discrete">
  <input class="mdc-slider__input" type="range" min="0" max="50" value="20" step="10" name="rangeStart" aria-label="Discrete range slider demo">
  <input class="mdc-slider__input" type="range" min="20" max="100" value="50" step="10" name="rangeEnd" aria-label="Discrete range slider demo">
  <div class="mdc-slider__track">
    <div class="mdc-slider__track--inactive"></div>
    <div class="mdc-slider__track--active">
      <div class="mdc-slider__track--active_fill"></div>
    </div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__value-indicator-container" aria-hidden="true">
      <div class="mdc-slider__value-indicator">
        <span class="mdc-slider__value-indicator-text">
          20
        </span>
      </div>
    </div>
    <div class="mdc-slider__thumb-knob"></div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__value-indicator-container" aria-hidden="true">
      <div class="mdc-slider__value-indicator">
        <span class="mdc-slider__value-indicator-text">
          50
        </span>
      </div>
    </div>
    <div class="mdc-slider__thumb-knob"></div>
  </div>
</div>

Other variants

Disabled slider

To disable a slider, add the following:

• mdc-slider--disabled class on the root element
• disabled attribute on the input element

<div class="mdc-slider mdc-slider--disabled">
  <input class="mdc-slider__input" type="range" min="0" max="100" value="50" step="10" disabled name="volume" aria-label="Disabled slider demo">
  <div class="mdc-slider__track">
    <div class="mdc-slider__track--inactive"></div>
    <div class="mdc-slider__track--active">
      <div class="mdc-slider__track--active_fill"></div>
    </div>
  </div>
  <div class="mdc-slider__thumb">
    <div class="mdc-slider__thumb-knob"></div>
  </div>
</div>

Additional information

Initialization with custom ranges and values

When MDCSlider is initialized, it reads the input element's min, max, and value attributes if present, using them to set the component's internal min, max, and value properties.

Use these attributes to initialize the slider with a custom range and values, as shown below:

<div class="mdc-slider">
  <input class="mdc-slider__input" aria-label="Slider demo" min="0" max="100" value="75">
  <!-- ... -->
</div>

Setting slider position before component initialization

When MDCSlider is initialized, it updates the slider track and thumb positions based on the internal value(s). To set the correct track and thumb positions before component initialization, mark up the DOM as follows:

• Calculate rangePercentDecimal, the active track range as a percentage of the entire track, i.e. (valueEnd - valueStart) / (max - min). Set transform:scaleX(<rangePercentDecimal>) as an inline style on the mdc-slider__track--active_fill element.
• Calculate thumbEndPercent, the initial position of the end thumb as a percentage of the entire track. Set left:calc(<thumbEndPercent>% - 24px) as an inline style on the end thumb (mdc-slider__thumb) element (or right for RTL layouts).
• [Range sliders only] Calculate thumbStartPercent, the initial position of the start thumb as a percentage of the entire track. Set left:calc(<thumbStartPercent>% - 24px) as an inline style on the start thumb (mdc-slider__thumb) element (or right for RTL layouts).
• [Range sliders only] Using the previously calculated thumbStartPercent, set left:<thumbStartPercent>% as an inline style on the mdc-slider__track--active_fill element (or right for RTL layouts).

Additionally, the MDCSlider component should be initialized with skipInitialUIUpdate set to true.

Range slider example

This is an example of a range slider with internal values of [min, max] = [0, 100] and [start, end] = [30, 70], and a minimum range of 10.

<div class="mdc-slider mdc-slider--range" data-min-range="10">
  <input class="mdc-slider__input" type="range" min="0" max="60" value="30" name="rangeStart" aria-label="Range slider demo">
  <input class="mdc-slider__input" type="range" min="40" max="100" value="70" name="rangeEnd" aria-label="Range slider demo">
  <div class="mdc-slider__track">
    <div class="mdc-slider__track--inactive"></div>
    <div class="mdc-slider__track--active">
      <div class="mdc-slider__track--active_fill"
           style="transform:scaleX(.4); left:30%"></div>
    </div>
  </div>
  <div class="mdc-slider__thumb" style="left:calc(30%-24px)">
    <div class="mdc-slider__thumb-knob"></div>
  </div>
  <div class="mdc-slider__thumb" style="left:calc(70%-24px)">
    <div class="mdc-slider__thumb-knob"></div>
  </div>
</div>

API

Sass mixins

Mixin | Description --- | --- track-active-color($color) | Sets the color of the active track. track-inactive-color($color, $opacity) | Sets the color and opacity of the inactive track. thumb-color($color) | Sets the color of the thumb. thumb-ripple-color($color) | Sets the color of the thumb ripple. tick-mark-active-color($color) | Sets the color of tick marks on the active track. tick-mark-inactive-color($color) | Sets the color of tick marks on the inactive track. value-indicator-color($color, $opaicty) | Sets the color and opacity of the value indicator. value-indicator-text-color($color, $opaicty) | Sets the color of the value indicator text.

MDCSlider events

Event name | event.detail | Description --- | --- | --- MDCSlider:change | MDCSliderChangeEventDetail | Emitted when a value has been changed and committed from a user event. Mirrors the native change event: https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/change_event MDCSlider:input | MDCSliderChangeEventDetail | Emitted when a value has been changed from a user event. Mirrors the native input event: https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/input_event

MDCSlider methods

Method Signature | Description --- | --- getValueStart() => number | Gets the value of the start thumb (only applicable for range sliders). setValueStart(valueStart: number) => void | Sets the value of the start thumb (only applicable for range sliders). getValue() => number | Gets the value of the thumb (for single point sliders), or the end thumb (for range sliders). setValue(value: number) => void | Sets the value of the thumb (for single point sliders), or the end thumb (for range sliders). getDisabled() => boolean | Gets the disabled state of the slider. setDisabled(disabled: boolean) => void | Sets the disabled state of the slider. setValueToAriaValueTextFn((mapFn: ((value: number) => string) \| null) => void | Sets a function that maps the slider value to value of the aria-valuetext attribute on the thumb element. If not set, the aria-valuetext attribute is unchanged when the value changes.

Usage within frameworks

If you are using a JavaScript framework such as React or Angular, you can create a slider for your framework. Depending on your needs, you can use the Simple Approach: Wrapping MDC Web Vanilla Components, or the Advanced Approach: Using Foundations and Adapters. Please follow the instructions here.

See MDCSliderAdapter and MDCSliderFoundation for up-to-date code documentation of slider foundation API's.