@shortcm/select

0.44.1 • Public • Published

Select Menus

MDC Select provides Material Design single-option select menus. It supports using the browser's native <select> element, or a MDC Menu. It is fully accessible, and fully RTL-aware.

Design & API Documentation

Installation

npm install @material/select

Basic Usage

This section documents how to use a MDC Select with a native <select> element. For information on using MDC Select with a MDC Menu, see the Variants section below.

HTML Structure

<div class="mdc-select">
  <i class="mdc-select__dropdown-icon"></i>
  <select class="mdc-select__native-control">
    <option value="" disabled selected></option>
    <option value="grains">
      Bread, Cereal, Rice, and Pasta
    </option>
    <option value="vegetables">
      Vegetables
    </option>
    <option value="fruit">
      Fruit
    </option>
  </select>
  <label class="mdc-floating-label">Pick a Food Group</label>
  <div class="mdc-line-ripple"></div>
</div>

Styles

For the native select, you can simply include the mdc-select Sass file.

@import "@material/select/mdc-select";

JavaScript Instantiation

import {MDCSelect} from '@material/select';

const select = new MDCSelect(document.querySelector('.mdc-select'));

select.listen('MDCSelect:change', () => {
  alert(`Selected option at index ${select.selectedIndex} with value "${select.value}"`);
});

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

Variants

Enhanced Select

The enhanced select uses an MDCMenu component instance to contain the list of options, but uses the data-value attribute instead of value to represent the options' values.

Note: The data-value attribute must be present on each option.

The enhanced select requires that you set the width of the root element (containing the mdc-select class) as well as setting the width of the mdc-select__menu element to match. This is best done through the use of another class (e.g. demo-width-class in the example HTML and CSS below).

If you are using the enhanced select within an HTML form, you can include a hidden <input> element under the root mdc-select element, and it will be synchronized when the value is updated via user interaction or programmatically.

<div class="mdc-select demo-width-class">
  <input type="hidden" name="enhanced-select">
  <i class="mdc-select__dropdown-icon"></i>
  <div class="mdc-select__selected-text"></div>
  <div class="mdc-select__menu mdc-menu mdc-menu-surface demo-width-class">
    <ul class="mdc-list">
      <li class="mdc-list-item mdc-list-item--selected" data-value="" aria-selected="true"></li>
      <li class="mdc-list-item" data-value="grains">
        Bread, Cereal, Rice, and Pasta
      </li>
      <li class="mdc-list-item" data-value="vegetables">
        Vegetables
      </li>
      <li class="mdc-list-item" data-value="fruit">
        Fruit
      </li>
    </ul>
  </div>
  <span class="mdc-floating-label">Pick a Food Group</span>
  <div class="mdc-line-ripple"></div>
</div>

When using the enhanced select, you will also need to load the Menu and List components' styles.

@import "@material/list/mdc-list";
@import "@material/menu-surface/mdc-menu-surface";
@import "@material/menu/mdc-menu";
@import "@material/select/mdc-select";

.demo-width-class {
  width: 400px;
}

Usability Notes

The enhanced select provides a look and feel more consistent with the rest of Material Design, but there are some trade-offs to consider when choosing it over the native <select> element.

  • Keyboard type-ahead: Native selects typically benefit from OS-implemented keyboard type-ahead support (i.e. they will automatically select an item starting with the letters typed). This is not present in the enhanced select.
  • Mobile UI: Mobile OSes implement native selects as a modal dialog or bottom sheet. The enhanced select always uses an MDC Menu, which may not provide an optimal experience for small screens.

Accessibility (a11y)

In order to have an accessible component for users, it's recommended that you follow the WAI-ARIA example for Collapsible Dropdown Listbox. The following is an example of the enhanced select component with all of the necessary aria attributes.

<div class="mdc-select">
  <input type="hidden" name="enhanced-select">
  <i class="mdc-select__dropdown-icon"></i>
  <div id="demo-selected-text" class="mdc-select__selected-text" role="button" aria-haspopup="listbox" aria-labelledby="demo-label demo-selected-text">Vegetables</div>
  <div class="mdc-select__menu mdc-menu mdc-menu-surface" role="listbox">
    <ul class="mdc-list">
      <li class="mdc-list-item mdc-list-item--selected" data-value="" role="option"></li>
      <li class="mdc-list-item" data-value="grains" role="option">
        Bread, Cereal, Rice, and Pasta
      </li>
      <li class="mdc-list-item mdc-list-item--disabled" data-value="vegetables" aria-selected="true" aria-disabled="true" role="option">
        Vegetables
      </li>
      <li class="mdc-list-item" data-value="fruit" role="option">
        Fruit
      </li>
    </ul>
  </div>
  <span id="demo-label" class="mdc-floating-label mdc-floating-label--float-above">Pick a Food Group</span>
  <div class="mdc-line-ripple"></div>
</div>

Outlined Select

The Select Outlined variant uses the mdc-notched-outline in place of the mdc-line-ripple element and adds the mdc-select--outlined modifier class on the root element. All other elements for each type of select remain the same.

<div class="mdc-select mdc-select--outlined">
  <!-- Other elements from the native or enhanced select remain. -->
   <div class="mdc-notched-outline">
     <div class="mdc-notched-outline__leading"></div>
     <div class="mdc-notched-outline__notch">
       <label class="mdc-floating-label">Pick a Food Group</label>
     </div>
     <div class="mdc-notched-outline__trailing"></div>
   </div>
</div>

Additional Information

Select with pre-selected option

When dealing with a select component that has a pre-selected value, include the mdc-floating-label--float-above modifier class on the mdc-floating-label element, and add the selected attribute to the selected option. This will ensure that the label moves out of the way of the select's value and prevents a Flash Of Unstyled Content (FOUC).

<div class="mdc-select">
  <i class="mdc-select__dropdown-icon"></i>
  <select class="mdc-select__native-control">
    <option value="vegetables">
      Vegetables
    </option>
    <option value="fruit">
      Fruit
    </option>
    <option value="dairy" selected>
      Milk, Yogurt, and Cheese
    </option>
  </select>
  <label class="mdc-floating-label mdc-floating-label--float-above">Pick a Food Group</label>
  <div class="mdc-line-ripple"></div>
</div>

The enhanced select works in a similar way, but uses the mdc-list-item--selected class to set the selected item. The enhanced select also needs the text from the selected element copied to the mdc-select__selected-text element.

<div class="mdc-select demo-width-class">
  <input type="hidden" name="enhanced-select">
  <i class="mdc-select__dropdown-icon"></i>
  <div class="mdc-select__selected-text">Vegetables</div>
  <div class="mdc-select__menu demo-width-class mdc-menu mdc-menu-surface">
    <ul class="mdc-list">
      <li class="mdc-list-item" data-value=""></li>
      <li class="mdc-list-item" data-value="grains">
        Bread, Cereal, Rice, and Pasta
      </li>
      <li class="mdc-list-item mdc-list-item--selected" data-value="vegetables" aria-selected="true">
        Vegetables
      </li>
      <li class="mdc-list-item" data-value="fruit">
        Fruit
      </li>
    </ul>
  </div>
  <span class="mdc-floating-label mdc-floating-label--float-above">Pick a Food Group</span>
  <div class="mdc-line-ripple"></div>
</div>

Using the floating label as the placeholder

By default, <select> elements will select their first enabled option. In order to initially display a placeholder instead, add an initial <option> element with the selected attribute set (and optionally disabled, if the field is required), and with value set to "".

<option value="" disabled selected></option>

For the enhanced select, simply leave the mdc-select__selected-text element empty and don't specify an element as selected. If leaving the field empty should be a valid option, include an mdc-list-item element at the beginning of the list with an empty data-value attribute.

<li class="mdc-list-item mdc-list-item--selected" aria-selected="true" role="option" data-value=""></li>

Disabled select

To initially render a MDC Select in a disabled state, add the mdc-select--disabled class to the mdc-select element, and add the disabled attribute to the <select> element.

<div class="mdc-select mdc-select--disabled">
  <i class="mdc-select__dropdown-icon"></i>
  <select class="mdc-select__native-control" disabled>
    ...
  </select>
  <label class="mdc-floating-label">Pick a Food Group</label>
  <div class="mdc-line-ripple"></div>
</div>

For the enhanced select, add the mdc-select--disabled class to the mdc-select element, and add the disabled attribute to the hidden <input> element if present.

<div class="mdc-select mdc-select--disabled">
  <input type="hidden" name="enhanced-select" disabled>
  <i class="mdc-select__dropdown-icon"></i>
  <div class="mdc-select__selected-text"></div>
  <div class="mdc-select__menu mdc-menu mdc-menu-surface">
    ...
  </div>
  <span class="mdc-floating-label">Pick a Food Group</span>
  <div class="mdc-line-ripple"></div>
</div>

Disabled options

For the native select, simply add the disabled attribute to individual options to disable them.

<div class="mdc-select">
  <select class="mdc-select__native-control">
    <option value="grains">
      Bread, Cereal, Rice, and Pasta
    </option>
    <option value="vegetables" disabled>
      Vegetables
    </option>
    <option value="fruit">
      Fruit
    </option>
  </select>
  <label class="mdc-floating-label">Pick a Food Group</label>
  <div class="mdc-line-ripple"></div>
</div>

For the enhanced select, you should add the mdc-list-item--disabled class to list items that are disabled. Unlike the native select, disabled list items are removed from the list items index, and are ignored entirely. You cannot programmatically select a disabled list item in the enhanced select.

<div class="mdc-select">
  <input type="hidden" name="enhanced-select">
  <i class="mdc-select__dropdown-icon"></i>
  <div class="mdc-select__selected-text">Vegetables</div>
  <div class="mdc-select__menu mdc-menu mdc-menu-surface">
    <ul class="mdc-list">
      <li class="mdc-list-item" data-value=""></li>
      <li class="mdc-list-item" data-value="grains">
        Bread, Cereal, Rice, and Pasta
      </li>
      <li class="mdc-list-item mdc-list-item--selected mdc-list-item--disabled" data-value="vegetables">
        Vegetables
      </li>
      <li class="mdc-list-item" data-value="fruit">
        Fruit
      </li>
    </ul>
  </div>
  <span class="mdc-floating-label mdc-floating-label--float-above">Pick a Food Group</span>
  <div class="mdc-line-ripple"></div>
</div>

Select with Helper Text

The helper text provides supplemental information and/or validation messages to users. It appears when the select element is focused and disappears on blur by default, or it can be persistent. See here for more information on using helper text.

Select with Leading Icons

Leading icons can be added within the default or outlined variant of MDC Select as visual indicators as well as interaction targets. See here for more information on using icons.

Style Customization

CSS Classes

Class Description
mdc-select Mandatory.
mdc-select__menu Mandatory when using the enhanced select. This class should be placed on the mdc-menu element within the mdc-select element.
mdc-select__dropdown-icon Mandatory. Should be placed on an i element within the mdc-select element. Used for the dropdown arrow svg and animation.
mdc-select__icon Optional. Should be placed on an i or svg element within the mdc-select element. Used for the leading icon.
mdc-select--disabled Optional. Styles the select as disabled. This class should be applied to the root element when the disabled attribute is applied to the <select> element.
mdc-select--outlined Optional. Styles the select as outlined select.
mdc-select__native-control Mandatory for the native select. The native <select> element.
mdc-select__selected-text Mandatory for the enhanced select. This class should be placed on a div within the mdc-select element.
mdc-select--with-leading-icon Styles the select as a select with a leading icon.

Note: To further customize the MDCMenu or the MDCList component contained within the select, please refer to their respective documentation.

Sass Mixins

Mixins should be included in the context of a custom class applied to the component's root element, e.g. .my-select.

Mixin Description
mdc-select-ink-color($color) Customizes the color of the selected item displayed in the select.
mdc-select-container-fill-color($color) Customizes the background color of the select.
mdc-select-label-color($color) Customizes the label color of the select in the unfocused state.
mdc-select-focused-label-color($color) Customizes the label color of the select when focused.
mdc-select-bottom-line-color($color) Customizes the color of the default bottom line of the select.
mdc-select-focused-bottom-line-color($color) Customizes the color of the bottom line of the select when focused.
mdc-select-shape-radius($radius, $rtl-reflexive) Sets rounded shape to boxed select variant with given radius size. Set $rtl-reflexive to true to flip radius values in RTL context, defaults to false.
mdc-select-hover-bottom-line-color($color) Customizes the color of the bottom line when the select is hovered.
mdc-select-outline-color($color) Customizes the color of the notched outline.
mdc-select-outline-shape-radius($radius, $rtl-reflexive) Sets the border radius of of the outlined select variant. Set $rtl-reflexive to true to flip radius values in RTL context, defaults to false.
mdc-select-focused-outline-color($color) Customizes the color of the outline of the select when focused.
mdc-select-hover-outline-color($color) Customizes the color of the outline when the select is hovered.

NOTE: To further customize the floating label, please see the floating label documentation.

MDCSelect API

The MDCSelect component API is modeled after a subset of the HTMLSelectElement functionality.

Property Type Description
value string The value/data-value of the currently selected option.
selectedIndex number The index of the currently selected option. Set to -1 if no option is currently selected. Changing this property will update the select element.
disabled boolean Whether or not the component is disabled. Setting this sets the disabled state on the component.
valid boolean Whether or not the component is in a valid state. Setting this updates styles on the component, but does not affect the native validity state.
required boolean Whether or not the component is required. Setting this updates the required or aria-required attribute on the component and enables validation.
leadingIconAriaLabel string (write-only) Proxies to the foundation's setLeadingIconAriaLabel method.
leadingIconContent string (write-only) Proxies to the foundation's setLeadingIconContent method.
helperTextContent string (write-only) Proxies to the foundation's setHelperTextContent method when set.

Events

Event Name Data Description
MDCSelect:change {value: string, index: number} Used to indicate when an element has been selected. This event also includes the value of the item and the index.

Usage within Web Frameworks

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

MDCSelectAdapter

Method Signature Description
addClass(className: string) => void Adds a class to the root element.
removeClass(className: string) => void Removes a class from the root element.
hasClass(className: string) => boolean Returns true if the root element has the className in its classList.
activateBottomLine() => void Activates the bottom line component.
deactivateBottomLine() => void Deactivates the bottom line component.
getValue() => string Returns the value selected option on the select element and the data-value of the selected list item on the enhanced select.
floatLabel(value: boolean) => void Floats or defloats label.
getLabelWidth() => number Returns the offsetWidth of the label element.
hasOutline() => boolean Returns true if the select has the notched outline element.
notchOutline(labelWidth: number) => void Switches the notched outline element to its "notched state."
closeOutline() => void Switches the notched outline element to its closed state.
openMenu() => void Causes the menu element in the enhanced select to open.
closeMenu() => void Causes the menu element in the enhanced select to close.
setValue(value: string) => void Sets the value of the select or text content of the selected-text element.
isMenuOpen() => boolean Returns true if the menu is currently opened in the enhanced select.
setSelectedIndex(index: number) => void Selects the option or list item at the specified index.
setDisabled(isDisabled: boolean) => void Enables or disables the native or enhanced select.
setRippleCenter(normalizedX: number) => void Sets the line ripple center to the provided normalizedX value.
notifyChange(value: string) => void Emits the MDCSelect:change event when an element is selected.
checkValidity() => boolean Returns whether the component is currently valid, using the native select's checkValidity or equivalent logic for the enhanced select.
setValid(isValid: boolean) => void Adds or removes invalid styles.

MDCSelectFoundation

Method Signature Description
notchOutline(openNotch: boolean) => void Opens/closes the notched outline.
setDisabled(isDisabled: boolean) => void Updates appearance based on disabled state. This must be called whenever the disabled state changes.
handleFocus() => void Handles a focus event on the select element.
handleBlur() => void Handles a blur event on the select element.
handleClick(normalizedX: number) => void Sets the line ripple center to the normalizedX for the line ripple.
handleChange() => void Handles a change to the select element's value. This must be called both for change events and programmatic changes requested via the component API.
handleKeydown(event: KeyboardEvent) => void Handles opening the menu (enhanced select) when the mdc-select__selected-text element is focused and the user presses the Enter or Space key.
setSelectedIndex(index: number) => void Handles setting the mdc-select__selected-text element and closing the menu (enhanced select only). Also causes the label to float and outline to notch if needed.
setValue(value: string) => void Handles setting the value through the adapter and causes the label to float and outline to notch if needed.
getValue() => string Handles getting the value through the adapter.
setValid(isValid: boolean) => void Sets the valid state through the adapter.
isValid() => boolean Gets the valid state through the adapter's checkValidity API.
layout() => void Handles determining if the notched outline should be notched.
setLeadingIconAriaLabel(label: string) => void Sets the aria label of the leading icon.
setLeadingIconContent(content: string) => void Sets the text content of the leading icon.
setHelperTextContent(content: string) => void Sets the content of the helper text.

MDCSelectFoundation supports multiple optional sub-elements: helper text and icon. The foundations of these sub-elements must be passed in as constructor arguments to MDCSelectFoundation.

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  • lyubov-voloshko
  • kostenko