Lists

Lists are continuous, vertical indexes of text or images.

Design & API Documentation

Installation

npm install @limetech/mdc-list

Basic Usage

HTML Structure

<ul class="mdc-list">
  <li class="mdc-list-item" tabindex="0">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
</ul>

Styles

@import "@limetech/mdc-list/mdc-list";

JavaScript

MDC List includes an optional JavaScript component which can be used for keyboard interaction and accessibility.

import {MDCList} from '@limetech/mdc-list';

const list = new MDCList(document.querySelector('.mdc-list'));

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

Note that the JS component does not automatically instantiate ripples on list items. If you wish to include the fully-upgraded ripple effect on list items, you must instantiate MDCRipple on each item:

import {MDCRipple} from '@limetech/mdc-ripple';

const listItemRipples = list.listElements.map((listItemEl) => new MDCRipple(listItemEl));

Variants

Two-Line List

You can use the mdc-list--two-line combined with some extra markup around the text to style a list in the double line list style as defined by the spec (see "Double line").

<ul class="mdc-list mdc-list--two-line">
  <li class="mdc-list-item" tabindex="0">
    <span class="mdc-list-item__text">
      <span class="mdc-list-item__primary-text">Two-line item</span>
      <span class="mdc-list-item__secondary-text">Secondary text</span>
    </span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">
      <span class="mdc-list-item__primary-text">Two-line item</span>
      <span class="mdc-list-item__secondary-text">Secondary text</span>
    </span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">
      <span class="mdc-list-item__primary-text">Two-line item</span>
      <span class="mdc-list-item__secondary-text">Secondary text</span>
    </span>
  </li>
</ul>

NOTE: Make sure there are no white-space characters before primary and secondary text content.

List Groups

Multiple related lists can be grouped together using the mdc-list-group class on a containing element.

<div class="mdc-list-group">
  <h3 class="mdc-list-group__subheader">List 1</h3>
  <ul class="mdc-list">
    <li class="mdc-list-item" tabindex="0">
      <span class="mdc-list-item__text">line item</span>
    </li>
    <li class="mdc-list-item">
      <span class="mdc-list-item__text">line item</span>
    </li>
    <li class="mdc-list-item">
      <span class="mdc-list-item__text">line item</span>
    </li>
  </ul>
  <h3 class="mdc-list-group__subheader">List 2</h3>
  <ul class="mdc-list">
    <li class="mdc-list-item">
      <span class="mdc-list-item__text">line item</span>
    </li>
    <li class="mdc-list-item">
      <span class="mdc-list-item__text">line item</span>
    </li>
    <li class="mdc-list-item">
      <span class="mdc-list-item__text">line item</span>
    </li>
  </ul>
</div>

List Dividers

MDC List contains an mdc-list-divider class which can be used as full-width or inset subdivisions either within lists themselves, or standalone between related groups of content.

<ul class="mdc-list">
  <li class="mdc-list-item" tabindex="0">
    <span class="mdc-list-item__text">Item 1 - Division 1</span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Item 2 - Division 1</span>
  </li>
  <li role="separator" class="mdc-list-divider"></li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Item 1 - Division 2</span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Item 2 - Division 2</span>
  </li>
</ul>

NOTE: the role="separator" attribute on the list divider. It is important to include this so that assistive technology can be made aware that this is a presentational element and is not meant to be included as an item in a list. Note that separator is indeed a valid role for li elements.

OR

<ul class="mdc-list">
  <li class="mdc-list-item" tabindex="0">
    <span class="mdc-list-item__text">Item 1 - List 1</span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Item 2 - List 1</span>
  </li>
</ul>
<hr class="mdc-list-divider">
<ul class="mdc-list">
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Item 1 - List 2</span>
  </li>
  <li class="mdc-list-item">
    <span class="mdc-list-item__text">Item 2 - List 2</span>
  </li>
</ul>

Single Selection List

MDC List can handle selecting/deselecting list elements based on click or keyboard actions. When enabled, the space and enter keys (or click event) will trigger a single list item to become selected and any other previously selected element to become deselected.

<ul id="my-list" class="mdc-list" role="listbox">
  <li class="mdc-list-item" role="option" tabindex="0">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item" role="option">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item" role="option">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
</ul>

const list = new MDCList(document.getElementById('my-list'));
list.singleSelection = true;

Pre-selected list item

When rendering the list with a pre-selected list item, the list item that needs to be selected should contain the mdc-list-item--selected or mdc-list-item--activated class before creating the list. Please see Accessibility section for appropriate aria attributes.

<ul id="my-list" class="mdc-list" role="listbox">
  <li class="mdc-list-item" role="option" aria-selected="false">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item mdc-list-item--selected" role="option" aria-selected="true" tabindex="0">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item" role="option" aria-selected="false">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
</ul>

const list = new MDCList(document.getElementById('my-list'));
list.singleSelection = true;

List with radio group

When rendering list radio group with pre-selected radio button the selected list item should contain aria-checked set to true and the native radio input element contains checked attribute, all other list items should have aria-checked set to false. The list root contains role="radiogroup" whereas each list item within radio group contains role="radio".

<ul class="mdc-list" role="radiogroup">
  <li class="mdc-list-item" role="radio" aria-checked="false">
    <span class="mdc-list-item__graphic">
      <div class="mdc-radio">
        <input class="mdc-radio__native-control"
              type="radio"
              id="demo-list-radio-item-1"
              name="demo-list-radio-item-group"
              value="1">
        <div class="mdc-radio__background">
          <div class="mdc-radio__outer-circle"></div>
          <div class="mdc-radio__inner-circle"></div>
        </div>
      </div>
    </span>
    <label class="mdc-list-item__text" for="demo-list-radio-item-1">Option 1</label>
  </li>
  <li class="mdc-list-item" role="radio" aria-checked="true" tabindex="0">
    <span class="mdc-list-item__graphic">
      <div class="mdc-radio">
        <input class="mdc-radio__native-control"
              type="radio"
              id="demo-list-radio-item-2"
              name="demo-list-radio-item-group"
              value="2"
              checked>
        <div class="mdc-radio__background">
          <div class="mdc-radio__outer-circle"></div>
          <div class="mdc-radio__inner-circle"></div>
        </div>
      </div>
    </span>
    <label class="mdc-list-item__text" for="demo-list-radio-item-2">Option 2</label>
  </li>
  <li class="mdc-list-item" role="radio" aria-checked="false">
    <span class="mdc-list-item__graphic">
      <div class="mdc-radio">
        <input class="mdc-radio__native-control"
              type="radio"
              id="demo-list-radio-item-3"
              name="demo-list-radio-item-group"
              value="3">
        <div class="mdc-radio__background">
          <div class="mdc-radio__outer-circle"></div>
          <div class="mdc-radio__inner-circle"></div>
        </div>
      </div>
    </span>
    <label class="mdc-list-item__text" for="demo-list-radio-item-3">Option 3</label>
  </li>
</ul>

List with checkbox items

When rendering list with checkbox items all pre-selected list items should contain aria-checked set to true and the native checkbox input element should contain checked attribute, all other list items should have aria-checked set to false. Each list item in checkbox list contains role="checkbox" attribute and the list root should contain role="group" and aria-label attributes.

<ul class="mdc-list" role="group" aria-label="List with checkbox items">
  <li class="mdc-list-item" role="checkbox" aria-checked="false">
    <span class="mdc-list-item__graphic">
      <div class="mdc-checkbox">
        <input type="checkbox"
                class="mdc-checkbox__native-control"
                id="demo-list-checkbox-item-1"  />
        <div class="mdc-checkbox__background">
          <svg class="mdc-checkbox__checkmark"
                viewBox="0 0 24 24">
            <path class="mdc-checkbox__checkmark-path"
                  fill="none"
                  d="M1.73,12.91 8.1,19.28 22.79,4.59"/>
          </svg>
          <div class="mdc-checkbox__mixedmark"></div>
        </div>
      </div>
    </span>
    <label class="mdc-list-item__text" for="demo-list-checkbox-item-1">Option 1</label>
  </li>
  <li class="mdc-list-item" role="checkbox" aria-checked="true" tabindex="0">
    <span class="mdc-list-item__graphic">
        <div class="mdc-checkbox">
            <input type="checkbox"
                    class="mdc-checkbox__native-control"
                    id="demo-list-checkbox-item-2"
                    checked />
            <div class="mdc-checkbox__background">
              <svg class="mdc-checkbox__checkmark"
                    viewBox="0 0 24 24">
                <path class="mdc-checkbox__checkmark-path"
                      fill="none"
                      d="M1.73,12.91 8.1,19.28 22.79,4.59"/>
              </svg>
              <div class="mdc-checkbox__mixedmark"></div>
            </div>
          </div>
    </span>
    <label class="mdc-list-item__text" for="demo-list-checkbox-item-2">Option 2</label>
  </li>
  <li class="mdc-list-item" role="checkbox" aria-checked="false">
    <span class="mdc-list-item__graphic">
        <div class="mdc-checkbox">
            <input type="checkbox"
                    class="mdc-checkbox__native-control"
                    id="demo-list-checkbox-item-3" />
            <div class="mdc-checkbox__background">
              <svg class="mdc-checkbox__checkmark"
                    viewBox="0 0 24 24">
                <path class="mdc-checkbox__checkmark-path"
                      fill="none"
                      d="M1.73,12.91 8.1,19.28 22.79,4.59"/>
              </svg>
              <div class="mdc-checkbox__mixedmark"></div>
            </div>
          </div>
    </span>
    <label class="mdc-list-item__text" for="demo-list-checkbox-item-3">Option 3</label>
  </li>
</ul>

The selectedIndex (that proxies foundation's setSelectedState()) accepts list of indexes in array format for list with checkbox items to set the selection state. It overwrites the current state with new selected state.

Style Customization

CSS Classes

CSS Class | Description --- | --- mdc-list | Mandatory, for the list element. mdc-list--non-interactive | Optional, disables interactivity affordances. mdc-list--dense | Optional, styles the density of the list, making it appear more compact. mdc-list--avatar-list | Optional, configures the leading tiles of each row to display images instead of icons. This will make the graphics of the list items larger. mdc-list--two-line | Optional, modifier to style list with two lines (primary and secondary lines). mdc-list-item | Mandatory, for the list item element. mdc-list-item__text | Mandatory. Wrapper for list item text content (displayed as middle column of the list item). mdc-list-item__primary-text | Optional, primary text for the list item. Should be the child of mdc-list-item__text. mdc-list-item__secondary-text | Optional, secondary text for the list item. Displayed below the primary text. Should be the child of mdc-list-item__text. mdc-list-item--disabled | Optional, styles the row in the disabled state. mdc-list-item--selected | Optional, styles the row in the selected* state. mdc-list-item--activated | Optional, styles the row in the activated* state. mdc-list-item__graphic | Optional, the first tile in the row (in LTR languages, the first column of the list item). Typically an icon or image. mdc-list-item__meta | Optional, the last tile in the row (in LTR languages, the last column of the list item). Typically small text, icon. or image. mdc-list-group | Optional, wrapper around two or more mdc-list elements to be grouped together. mdc-list-group__subheader | Optional, heading text displayed above each list in a group. mdc-list-divider | Optional, for list divider element. mdc-list-divider--padded | Optional, leaves gaps on each side of divider to match padding of list-item__meta. mdc-list-divider--inset | Optional, increases the leading margin of the divider so that it does not intersect the avatar column.

NOTE: The mdc-list-divider class can be used between list items OR between two lists (see respective examples under List Dividers).

NOTE: In Material Design, the selected and activated states apply in different, mutually-exclusive situations:

• Selected state should be applied on the .mdc-list-item when it is likely to frequently change due to user choice. E.g., selecting one or more photos to share in Google Photos.
• Activated state is more permanent than selected state, and will NOT change soon relative to the lifetime of the page. Common examples are navigation components such as the list within a navigation drawer.

Sass Mixins

Mixin | Description --- | --- mdc-list-item-primary-text-ink-color($color) | Sets the ink color of the primary text of the list item. mdc-list-item-secondary-text-ink-color($color) | Sets the ink color of the secondary text of the list item. mdc-list-item-graphic-fill-color($color) | Sets background ink color of the graphic element within list item. mdc-list-item-graphic-ink-color($color) | Sets ink color of the graphic element within list item. mdc-list-item-meta-ink-color($color) | Sets ink color of the meta element within list item. mdc-list-single-line-shape-radius($radius, $rtl-reflexive, $density-scale) | Sets the rounded shape to list item with given radius size. Set $rtl-reflexive to true to flip radius values in RTL context, defaults to false. Set $density-scale only when custom density is applied, defaults to $mdc-list-single-line-density-scale. mdc-list-divider-color($color) | Sets divider ink color. mdc-list-group-subheader-ink-color($color) | Sets ink color of subheader text within list group. mdc-list-item-disabled-text-color($color) | Sets the color of the text when the list item is disabled. mdc-list-item-disabled-text-opacity($opacity) | Sets the opacity of the text when the list item is disabled. mdc-list-single-line-density($density-scale) | Sets density scale to single line list variant. Supported density scales are -4, -3, -2, -1 and 0. mdc-list-single-line-height($height) | Sets height to single line list variant.

Accessibility

The MDCList JavaScript component implements the WAI-ARIA best practices for Listbox. This includes overriding the default tab behavior within the list component.

The tabindex should be set to 0 for first list item element or selected list item element, remaining list item elements should not have tabindex set.

Use role="listbox" only for single selection list, without this role the ul element is implicitely role="list". Do not use aria-orientation attribute for standard list (i.e., role="list"), use component's vertical property to set the orientation to vertical.

Single selection list supports aria-selected and aria-current attributes. List automatically detects the presence of these attributes and sets it to next selected list item based on which ARIA attribute you use (i.e., aria-selected or aria-current). Please see WAI-ARIA aria-current article for recommended usage and available attribute values.

As the user navigates through the list, any button and a elements within the list will receive tabindex="-1" when the list item is not focused. When the list item receives focus, the aforementioned elements will receive tabIndex="0". This allows for the user to tab through list item elements and then tab to the first element after the list. The Arrow, Home, and End keys should be used for navigating internal list elements. If singleSelection=true, the list will allow the user to use the Space or Enter keys to select or deselect a list item. The MDCList will perform the following actions for each key press. Since list interaction will toggle a radio button or checkbox within the list item, the list will not toggle tabindex for those elements.

Disabled list item will be included in the keyboard navigation. Please see Focusability of disabled controls section in ARIA practices article.

Key | Action --- | --- ArrowUp | When the list is in a vertical orientation, it will cause the previous list item to receive focus. ArrowDown | When the list is in a vertical orientation, it will cause the next list item to receive focus. ArrowLeft | When the list is in a horizontal orientation (default), it will cause the previous list item to receive focus. ArrowRight | When the list is in a horizontal orientation (default), it will cause the next list item to receive focus. Home | Will cause the first list item in the list to receive focus. End | Will cause the last list item in the list to receive focus. Space | Will cause the currently focused list item to become selected/deselected if singleSelection=true. Enter | Will cause the currently focused list item to become selected/deselected if singleSelection=true.

MDCList Properties and Methods

Property | Value Type | Description --- | --- | --- vertical | boolean (write-only) | Proxies to the foundation's setVerticalOrientation() method. listElements | Array<Element> (read-only) | Returns all list item elements including disabled list items. wrapFocus | boolean (write-only) | Proxies to the foundation's setWrapFocus() method. singleSelection | boolean (write-only) | Proxies to the foundation's setSingleSelection() method. selectedIndex | boolean | Proxies to the foundation's getSelectedIndex() and setSelectedIndex() methods.

Method Signature | Description --- | --- layout() => void | Recalculates layout and orientation. initializeListType() => void | Initialize selectedIndex value based on pre-selected checkbox list items, single selection or radio. setEnabled(itemIndex: number, isEnabled: boolean) => void | Updates the list item at itemIndex to the desired isEnabled state.

Events

Event Name | event.detail | Description --- | --- | --- MDCList:action | {index: number} | Indicates that a list item with the specified index has been activated.

Usage within Web Frameworks

If you are using a JavaScript framework, such as React or Angular, you can create a List 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.

Considerations for Advanced Approach

The MDCListFoundation expects the HTML to be setup a certain way before being used. This setup is a part of the layout() and singleSelection() functions within the index.js.

Setup in layout()

The default component requires that every list item receives a tabindex value so that it can receive focus (li elements cannot receive focus at all without a tabindex value). Any element not already containing a tabindex attribute will receive tabindex=-1. The first list item should have tabindex="0" so that the user can find the first element using the tab key, but subsequent tab keys strokes will cause focus to skip over the entire list. If the list items contain sub-elements that are focusable (button and a elements), these should also receive tabIndex="-1".

<ul id="my-list" class="mdc-list">
  <li class="mdc-list-item" tabindex="0">
    <span class="mdc-list-item__text">Single-line item</span>
    <button tabindex="-1"></button>
  </li>
  <li class="mdc-list-item" tabindex="-1">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item" tabindex="-1">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
</ul>

Setup in singleSelection()

When implementing a component that will use the single selection variant, the HTML should be modified to include the mdc-list-item--selected or mdc-list-item--activated class name, and the tabindex of the selected element should be 0. The first list item should have the tabindex updated to -1. The foundation method setSelectedIndex() should be called with the initially selected element immediately after the foundation is instantiated. Please see Accessibility section for appropriate aria attributes.

<ul id="my-list" class="mdc-list">
  <li class="mdc-list-item" tabindex="-1">
    <span class="mdc-list-item__text">Single-line item</span>
    <button tabindex="-1"></button>
    </li>
  <li class="mdc-list-item mdc-list-item--selected" aria-selected="true" tabindex="0">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
  <li class="mdc-list-item" tabindex="-1">
    <span class="mdc-list-item__text">Single-line item</span>
  </li>
</ul>

MDCListAdapter

Method Signature | Description --- | --- getListItemCount() => Number | Returns the total number of list items (elements with mdc-list-item class) that are direct children of the root_ element. getFocusedElementIndex() => Number | Returns the index value of the currently focused element. getListItemIndex(ele: Element) => Number | Returns the index value of the provided ele element. getAttributeForElementIndex(index: number, attribute: string) => string | null | Returns the attribute value of list item at given index. setAttributeForElementIndex(index: Number, attr: String, value: String) => void | Sets the attr attribute to value for the list item at index. addClassForElementIndex(index: Number, className: String) => void | Adds the className class to the list item at index. removeClassForElementIndex(index: Number, className: String) => void | Removes the className class to the list item at index. focusItemAtIndex(index: Number) => void | Focuses the list item at the index value specified. setTabIndexForListItemChildren(index: Number, value: Number) => void | Sets the tabindex attribute to value for each child button or anchor element in the list item at the index specified. hasRadioAtIndex(index: number) => boolean | Returns true if radio button is present at given list item index. hasCheckboxAtIndex(index: number) => boolean | Returns true if checkbox is present at given list item index. isCheckboxCheckedAtIndex(index: number) => boolean | Returns true if checkbox inside a list item is checked. setCheckedCheckboxOrRadioAtIndex(index: number, isChecked: boolean) => void | Sets the checked status of checkbox or radio at given list item index. notifyAction(index: number) => void | Notifies user action on list item including keyboard and mouse actions. isFocusInsideList() => boolean | Returns true if the current focused element is inside list root. isRootFocused() => boolean | Returns true if root element is focused. listItemAtIndexHasClass(index: number, className: string) => boolean | Returns true if list item at index has class className.

MDCListFoundation

Method Signature | Description --- | --- setWrapFocus(value: Boolean) => void | Sets the list to allow the up arrow on the first element to focus the last element of the list and vice versa. setVerticalOrientation(value: Boolean) => void | Sets the list to an orientation causing the keys used for navigation to change. true results in the Up/Down arrow keys being used. false results in the Left/Right arrow keys being used. setSingleSelection(value: Boolean) => void | Sets the list to be a selection list. Enables the enter and space keys for selecting/deselecting a list item. getSelectedIndex() => MDCListIndex | Gets the current selection state by returning selected index or list of indexes for checkbox based list. See types.ts for MDCListIndex type definition. setSelectedIndex(index: MDCListIndex) => void | Sets the selection state to given index or list of indexes if it is checkbox based list. See types.ts for MDCListIndex type definition. setUseActivatedClass(useActivated: boolean) => void | Sets the selection logic to apply/remove the mdc-list-item--activated class. handleFocusIn(evt: Event) => void | Handles the changing of tabindex to 0 for all button and anchor elements when a list item receives focus. handleFocusOut(evt: Event) => void | Handles the changing of tabindex to -1 for all button and anchor elements when a list item loses focus. handleKeydown(evt: Event) => void | Handles determining if a focus action should occur when a key event is triggered. handleClick(evt: Event) => void | Handles toggling the selected/deselected state for a list item when clicked. This method is only used by the single selection list. focusNextElement(index: number) => number | Handles focusing the next element using the current index. Returns focused element index. focusPrevElement(index: number) => number | Handles focusing the previous element using the current index. Returns focused element index. focusFirstElement() => number | Handles focusing the first element in a list. Returns focused element index. focusLastElement() => number | Handles focusing the last element in a list. Returns focused element index. setEnabled(itemIndex: number, isEnabled: Boolean) => void | Updates the list item's disabled state.