{/* Copyright 2020 Adobe. All rights reserved. This file is licensed to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */}

import {Layout} from '@react-spectrum/docs'; export default Layout;

import docs from 'docs:react-aria-components'; import {PropTable, HeaderInfo, TypeLink, PageDescription, StateTable, ContextTable} from '@react-spectrum/docs'; import styles from '@react-spectrum/docs/src/docs.css'; import packageData from 'react-aria-components/package.json'; import Anatomy from '/packages/react-aria/docs/meter/anatomy.svg'; import ChevronRight from '@spectrum-icons/workflow/ChevronRight'; import {Divider} from '@react-spectrum/divider'; import {ExampleCard} from '@react-spectrum/docs/src/ExampleCard'; import Label from '@react-spectrum/docs/pages/assets/component-illustrations/Label.svg'; import {StarterKits} from '@react-spectrum/docs/src/StarterKits';

category: Status keywords: [meter, progressbar, aria] type: component

Meter

<PageDescription>{docs.exports.Meter.description}</PageDescription>

Example

tsx

import {Meter, Label} from 'react-aria-components';

<Meter value={25}>
  {({percentage, valueText}) => <>
    <Label>Storage space</Label>
    <span className="value">{valueText}</span>
    <div className="bar">
      <div className="fill" style={{width: percentage + '%'}} />
    </div>
  </>}
</Meter>

css

@import "@react-aria/example-theme";

.react-aria-Meter {
  --fill-color: forestgreen;

  display: grid;
  grid-template-areas: "label value"
                       "bar bar";
  grid-template-columns: 1fr auto;
  gap: 4px;
  width: 250px;
  color: var(--text-color);

  .value {
    grid-area: value;
  }

  .bar {
    grid-area: bar;
    box-shadow: inset 0px 0px 0px 1px var(--border-color);
    forced-color-adjust: none;
    height: 10px;
    border-radius: 5px;
    overflow: hidden;
  }

  .fill {
    background: var(--fill-color);
    height: 100%;
  }
}

@media (forced-colors: active) {
  .react-aria-Meter {
    --fill-color: Highlight;
  }
}

</details>

Features

The <meter> HTML element can be used to build a meter, however it is very difficult to style cross browser. Meter helps achieve accessible meters that can be styled as needed.

Accessible – Follows the ARIA meter pattern, with fallback to progressbar where unsupported. A nested label is automatically associated with the meter semantically.
International – The value is formatted as a percentage or custom format according to the user's locale.

Note: Meters are similar to progress bars, but represent a quantity as opposed to progress over time. See ProgressBar for more details about progress bars.

Anatomy

Meters consist of a track element showing the full value in a range, a fill element showing the current value, a label, and an optional value label. The track and bar elements represent the value visually, while a wrapper element represents the meter to assistive technology using the meter ARIA role.

tsx

import {Meter, Label} from 'react-aria-components';

<Meter>
  <Label />
</Meter>

If there is no visual label, an aria-label or aria-labelledby prop must be passed instead to identify the element to screen readers.

Composed components

A Meter uses the following components, which may also be used standalone or reused in other components.

</section>

Starter kits

To help kick-start your project, we offer starter kits that include example implementations of all React Aria components with various styling solutions. All components are fully styled, including support for dark mode, high contrast mode, and all UI states. Each starter comes with a pre-configured Storybook that you can experiment with, or use as a starting point for your own component library.

Reusable wrappers

If you will use a Meter in multiple places in your app, you can wrap all of the pieces into a reusable component. This way, the DOM structure, styling code, and other logic are defined in a single place and reused everywhere to ensure consistency.

This example wraps Meter and all of its children together into a single component which accepts a label prop that is passed to the right place.

tsx

import type {MeterProps} from 'react-aria-components';

interface MyMeterProps extends MeterProps {
  label?: string
}

function MyMeter({label, ...props}: MyMeterProps) {
  return (
    <Meter {...props}>
      {({percentage, valueText}) => <>
        <Label>{label}</Label>
        <span className="value">{valueText}</span>
        <div className="bar">
          <div className="fill" style={{width: percentage + '%'}} />
        </div>
      </>}
    </Meter>
  );
}

<MyMeter label="Storage space" value={80} />

Value

Meters are controlled with the value prop. By default, the value prop represents the current percentage of progress, as the minimum and maximum values default to 0 and 100, respectively.

tsx

<MyMeter
  label="Storage space"
  value={25} />

Custom value scale

A custom value scale can be used by setting the minValue and maxValue props.

tsx

<MyMeter
  label="Widgets Used"
  minValue={50}
  maxValue={150}
  value={100} />

Labeling

Value formatting

Values are formatted as a percentage by default, but this can be modified by using the formatOptions prop to specify a different format. formatOptions is compatible with the option parameter of Intl.NumberFormat and is applied based on the current locale.

tsx

<MyMeter
  label="Currency"
  formatOptions={{style: 'currency', currency: 'JPY'}}
  value={60} />

Custom value label

The valueLabel prop allows the formatted value to be replaced with a custom string.

tsx

<MyMeter
  label="Space used"
  valueLabel="54 of 60GB"
  value={90} />

Props

Styling

React Aria components can be styled in many ways, including using CSS classes, inline styles, utility classes (e.g. Tailwind), CSS-in-JS (e.g. Styled Components), etc. By default, all components include a builtin className attribute which can be targeted using CSS selectors. These follow the react-aria-ComponentName naming convention.

css

.react-aria-Meter {
  /* ... */
}

A custom className can also be specified on any component. This overrides the default className provided by React Aria with your own.

jsx

<Meter className="my-meter">
</Meter>

The className and style props also accept functions which receive states for styling. This lets you dynamically determine the classes or styles to apply, which is useful when using utility CSS libraries like Tailwind.

jsx

<Meter className={({percentage}) => percentage > 50 ? 'bg-green-400' : 'bg-yellow-100'}>
  Item
</Meter>

The selectors and render props for each component used in a Meter are documented below.

Meter

A Meter can be targeted with the .react-aria-Meter CSS selector, or by overriding with a custom className. It supports the following states and render props:

Label

A Label can be targeted with the .react-aria-Label CSS selector, or by adding a custom className.

Advanced customization

Contexts

All React Aria Components export a corresponding context that can be used to send props to them from a parent element. This enables you to build your own compositional APIs similar to those found in React Aria Components itself. You can send any prop or ref via context that you could pass to the corresponding component. The local props and ref on the component are merged with the ones passed via context, with the local props taking precedence (following the rules documented in mergeProps).

This example sets the formatOptions via context, which applies to all nested meters.

tsx

import {MeterContext} from 'react-aria-components';

<MeterContext.Provider value={{formatOptions: {style: 'decimal'}}}>
  <MyMeter label="Widgets" value={28.5} />
  <MyMeter label="Cookies" value={68.75} />
</MeterContext.Provider>

Hooks

If you need to customize things further, such as customizing the DOM structure, you can drop down to the lower level Hook-based API. See useMeter for more details.