@material/feature-targeting

What is @material/feature-targeting?

@material/feature-targeting is a utility package from Material Components for the web (MDC Web) that provides a way to target specific CSS features. It allows developers to write CSS that is conditionally applied based on the presence of certain features, such as CSS variables or specific browser capabilities.

What are @material/feature-targeting's main functionalities?

CSS Variable Support

This feature allows you to write CSS rules that are only applied if the browser supports CSS variables. The mixin `supports-css-variables` checks for CSS variable support and applies the enclosed styles if the feature is available.

/* Import the feature targeting mixins */
@use '@material/feature-targeting/feature-targeting';

/* Define a CSS rule that only applies if CSS variables are supported */
@include feature-targeting.supports-css-variables() {
  .my-class {
    color: var(--my-color, black);
  }
}

Custom Property Fallbacks

This feature allows you to provide fallback styles for browsers that do not support CSS variables. The mixin `supports-css-variables` is used to conditionally apply the CSS variable-based styles, while the fallback styles are applied unconditionally.

/* Import the feature targeting mixins */
@use '@material/feature-targeting/feature-targeting';

/* Define a CSS rule with a fallback for browsers that do not support CSS variables */
.my-class {
  color: black;
  @include feature-targeting.supports-css-variables() {
    color: var(--my-color, black);
  }
}

Other packages similar to @material/feature-targeting

postcss-preset-env

postcss-preset-env is a PostCSS plugin that allows you to use future CSS features today. It includes polyfills for CSS features that are not yet widely supported, similar to how @material/feature-targeting provides conditional CSS based on feature support. However, postcss-preset-env is more comprehensive and supports a wider range of CSS features.

modernizr

Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user’s browser. It allows you to conditionally apply styles and scripts based on the presence of specific features, similar to @material/feature-targeting. Modernizr provides a more extensive set of feature detections and is not limited to CSS features.

README

Feature Targeting

MDC Feature Targeting provides infrastructure to allow CSS styles to be included or excluded categorically.

Most of the time, you shouldn't need to depend on mdc-feature-targeting directly. However, understanding it can be useful if you're interested in having more control over when certain types of MDC styles are emitted.

Installation

npm install @material/feature-targeting

Basic Usage

Styles

Authoring component styles:

@use "@material/feature-targeting";

@mixin my-component-core-styles($query: feature-targeting.all()) {
  $feat-structure: feature-targeting.create-target($query, structure);

  @include feature-targeting.targets($feat-structure) {
    // ...
  }
}

Consuming component styles:

@use "@material/feature-targeting";
@use "my-component-mixins";

// To include all styles (using the default of mdc-feature-all() defined above):
@include my-component-core-styles;

// Or, to include a specific subset of styles:
@include my-component-core-styles(structure);
@include my-component-core-styles(feature-targeting.any(color, typography));
// The above two @includes and the following @include would produce equivalent results:
@include my-component-core-styles(feature-targeting.without(animation));

Sass Mixins and Functions

Mixin	Description
targets($feature-targets...)	Conditionalizes content to only be emitted if the given feature target(s) is/are queried.

Function	Description
create-target($feature-query, $targeted-feature)	Returns a variable to be passed to targets in order to filter emitted styles.
all($feature-queries...)	Returns a query object which will result in emitting targets blocks that match all of the specified features. Passing no arguments results in all blocks being emitted, which is the most common use case.
any($feature-queries...)	Returns a query object which will result in emitting targets blocks that match any of the specified features. Passing no arguments results in no blocks being emitted.
without($feature-query)	Returns a query object which will result in emitting targets blocks that do not match the specified feature.

$feature-query and $feature-queries refer to one or more of the values listed below under Supported Features.

Supported Features

MDC Web's styles are currently split according to the following features:

• structure - All baseline styles that don't fit into any other category
• animation - Styles responsible for causing animations and transitions to occur
• color - Color-specific styles which rely on mdc-theme variables
• typography - Typography-specific styles which rely on mdc-typography

Changelog

10.0.0 (2021-02-05)

Bug Fixes

• data-table: fix style ordering wrt select & use new variable-width mixin (afb6889), closes #6599
• dialog: add property to customize suppressDefaultPressSelector (772cc10)
• linear-progress: fix RTL rendering (c7c5da2)
• list: add support for density scaling. (419e035)
• list: add support for non-interactive list roles. (fc8b045)
• list: ensure divider appears in IE high contrast mode. (eff7b46)
• menu: Remove anchorSize height from calculations when anchored to bottom (1631198)
• notched-outline: fix notched outline no-label style (99cfb6b)
• select: debounce click on anchor (b39094d)
• select: set aria-expanded false earlier when menu closes (df00c2b)
• slider: Add aria-hidden to value indicator container, to avoid duplicate value announcements for screenreader users. (9687353)
• slider: Adjust hidden input dimensions to take slider dimensions, such that screenreader focus indicators show a highlight around the entire slider. (fd22355)
• slider: Fire custom change event on input change. (07deaec)
• slider: Fix bug where value indicator container took space and could be hovered over / clicked when hidden. (832668d)
• slider: Mark ripple event handler as passive. Fixes #6746 (abdd100)
• slider: Remove big step options. Now that we're using a native range input, big step is not customizable - we follow browser defaults for big step. (ae27b44)
• slider: Update both thumbs' value indicator UI's if layout is invoked with undefined thumb. (489d4c2)
• slider: Use pointer-events: none instead of visibility: hidden to hide the value indicator container. Adding visibility: hidden removes the exit animation since the value indicator is immediately hidden. (a94bd8d)
• slider: Use mouse/touch events on iOS, to work around pointer events bug. (671d72d), closes #6715
• tabs: Expose min width mixin and set to 90px per spec. (c4ab987)
• theme: ensure either() works with false values (8e66dbf)
• tooltip: Adds "will-change" into CSS to prevent the tooltip from "jittering" when animating in. (7a003ac)
• tooltip: Change foundation to check for "dialog" on the anchor element's aria-haspopup attribute instead of checking for "true". (b8a1a58)
• tooltip: Clear hideTimeout in handleAnchorMouseEnter so that the tooltip will not be hidden if the user rapidly moves the mouse in and out of the anchor element. (365c693)
• tooltip: Fix rich tooltip tests to not use aria-describedby to associate rich tooltips with their anchor elements. This is because interactive rich tooltips should not be used with aria-describedby per a11y guidance. (251ac04)
• adjust meta baseline and update color mixins. (07f3e01)

Code Refactoring

• Remove MDC theme's deep-get, used sass:map's get API instead. (37fbae1)

Features

• banner: Add mobile-stacked variant support to banner. (a0b2db2)
• button: Add in HCM support to the mdc button as an opt-in mixin. (121e1f3)
• button: consolidate states into button mixins (637d15d)
• button: thread state keys through theme config (05f2496)
• checkbox: Add CSS custom properties to MDC checkbox for density theming (9244508)
• checkbox: Add validation to MDC Checkbox theme mixin (2d5f32d)
• circular-progress: do not require HTML without whitespaces (8648b82)
• dialog: add custom property for z-index (776c186)
• dialog: Adding styling for scroll bar dividers, and adding logic to show said dividers only when content is scrolled "behind" the header or footer of the dialog. (e383944)
• dialog: Adds and defines styling for the "header bar" on a full-screen dialog. (089de51)
• iconbutton: Add in HCM support to the mdc iconbutton as an opt-in mixin. (fd61b04)
• linear-progress: remove aria-valuemin/max attrs for indeterminate (4321323)
• list: support ctrl + a keyboard shortcut (eefef49), closes #6366
• list: Update the MDC component for List Evolution. (766981c)
• menu,select: enable fixed menu position in mwc-select (b9adb7a), closes #2062
• select: add mixin for variable width (30c11bf)
• slider: Add hidden input to slider, to support forms submission. This is also prep for moving to use an <input type="range"> behind the scenes, in order to support touch-based AT's. (b98d15d)
• slider: Modify continuous slider to use step value by default, and give clients the option to customize step value for continuous sliders. (7ad038e)
• slider: Use input with type="range" to back slider component. This ensures that sliders can be adjusted with touch-based assistive technologies, as the current ARIA spec for sliders is not compatible with e.g. TalkBack/Android. (9083b7d)
• snackbar: Add 1px transparent border for high contrast support (15a4d40)
• theme: add either() utility function (5268222)
• theme: add validation option to disallow custom properties (fec7b42)
• theme: Added validation mixin to validate provided theme configuration keys (1c156d6)
• theme: allow lists in replace maps (d2959b1)
• theme: emit CSS var() declarations when provided a standalone custom prop (1a3a396)
• tooltip: Add positioning adjustment and position specification for rich tooltips. Rich tooltips default to the END position and does not support CENTER positioning. (384a8ee)
• tooltip: Added persistent variant for rich tooltips that shows/hides based on mouse clicks on the anchor element. Clicks on elements other than the anchor will also hide the persistent variant. (9775856)
• tooltip: Adds transform-origin on tooltip surface so tooltip entrance animation has a direction based on its alignment with the anchor element. (623af86)
• tooltip: Adjust tooltip position on scroll and resize events. This ensures that the tooltip remains pinned to the anchor element despite page movement. (a415276)
• tooltip: Adjusting tooltip positioning logic so that the tooltip remains within the viewport even if the anchor element is partially off-screen. (482ff90)
• tooltip: Change rich tooltip to use position absolute instead of fixed and rely on a position relative parent element so that if the parent has a transform, perspective, or filter property set to something other than none, the positioning would still work. (0c95c9f)
• tooltip: Define styling to set the full-screen dialog size depending on the viewport size. (fe13dd1)
• tooltip: Expose hide and isShown methods in the MDCTooltip component. This allows MDC clients to create their own class to enforce only one tooltip being shown at a time. (c5e18b0)
• tooltip: Hide rich tooltip if mouse leaves rich tooltip. Rich tooltip persists if mouse leaves rich tooltip and enters anchor. (6d8574f)
• tooltip: Reducing minimum threshold distance between tooltip and viewport from 32px to 8px. (23491cf)
• tooltip: Restore focus to the anchor element when the ESC button is pressed while the focus is in the tooltip for rich tooltips. Default rich tooltips should have focus restored to anchor and not have rich tooltips show. (eabf9d5)
• tooltip: Set up base sass for rich tooltip. Rich tooltips are currently in development and is not yet ready for use. (4ae94ff)
• tooltip: Set up rich tooltip to persist if mouse leaves anchor and enters rich tooltip. (c927a5d)
• tooltip: The aria-expanded attribute of the anchor element will only be changed for anchor elements with interactive rich tooltips. Non-interactive rich tooltip anchor elements do not have the aria-haspopup and aria-expanded attributes. (c5dda80)
• tooltip: When the anchor element blurs, the rich tooltip will only be hidden if the focus is changed to a non-rich tooltip element. (6871336)
• Added global variable to conditionally emit CSS selector fallback declarations (7b0e2b3)
• tooltip: When the rich tooltip element focuses out, hide the rich tooltip if the new focused element is not the anchor element or an element within the rich tooltip. (1085c3b)

BREAKING CHANGES

• theme: custom-properties.apply() has been renamed to declaration() to better align with css.declaration()
• tooltip: Added adapter methods:
  • getComputedStyleProperty(propertyName: string): string;
  • getParentBoundingRect(): ClientRect|null;
• tooltip: Added adapter method:
  • tooltipContainsElement(element: HTMLElement): boolean;
• Removed deep-get() API from mdc-theme, use sass:map's get() API instead.
• tooltip: Added adapter method:
  • anchorContainsElement(element: HTMLElement): boolean;
• slider: Slider is now backed by an input of type="range". Additionally, adapter methods (focusInput, isInputFocused, registerInputEventHandler, deregisterInputEventHandler) were added.
• tooltip: Added adapter methods:
  • setAnchorAttribute(attr: string, value: string): void;
  • registerEventHandler<K extends EventType>( evtType: K, handler: SpecificEventListener<K>): void;
  • deregisterEventHandler<K extends EventType>( evtType: K, handler: SpecificEventListener<K>): void;
• slider: Adds slider adapter methods (get/setInputValue, get/setInputAttribute, removeInputAttribute). Slider DOM structure now contains a hidden input.