# Progress

Show a task’s progress, or an indeterminate state while its progress is unknown.

```tsx title="basic.tsx"
import {
  Progress,
  ProgressIndicator,
  ProgressLabel,
  ProgressTrack,
  ProgressValue,
} from "@ui-sdk/react/progress"

function Example() {
  return (
    <Progress value={60}>
      <ProgressLabel>Exporting video</ProgressLabel>
      <ProgressValue />
      <ProgressTrack>
        <ProgressIndicator />
      </ProgressTrack>
    </Progress>
  )
}

export { Example }
```

Read the export bar. Its label and 60% value are available both visually and to a screen reader.

## Installation

```bash
npm install @ui-sdk/react @ui-sdk/core
```

## Composition

Use the following composition to build a `Progress`:

```text
Progress
├── ProgressLabel
├── ProgressValue
└── ProgressTrack
    └── ProgressIndicator
```

- `Progress` holds the value and range.
- `ProgressLabel` gives it a visible name. You can use `aria-label` on the root instead.
- `ProgressValue` displays the formatted value.
- `ProgressTrack` gives the bar its size, and `ProgressIndicator` fills it.

The value is already part of the root's accessible description. The visible value is hidden from screen readers to avoid reading it twice.

## Usage

Import the parts and put them together:

```tsx
<Progress value={40}>
  <ProgressLabel />
  <ProgressValue />
  <ProgressTrack>
    <ProgressIndicator />
  </ProgressTrack>
</Progress>
```

## Build Your Own

`@ui-sdk/react/progress` comes with a ready-made Progress. If you'd like to build your own, with your own names, start from the `progress` primitive in `@ui-sdk/core`:

```ts title="upload.ts"
"use client"

import { progress } from "@ui-sdk/core/progress"
import { createParts } from "@ui-sdk/react/primitive"

const {
  Root: Upload,
  Label: UploadLabel,
  Value: UploadValue,
  Track: UploadTrack,
  Indicator: UploadBar,
} = createParts(progress, {
  root: "div",
  label: "span",
  value: "span",
  track: "div",
  indicator: "div",
})

export { Upload, UploadBar, UploadLabel, UploadTrack, UploadValue }
```

```tsx
<Upload value={40}>
  <UploadLabel>Uploading photos</UploadLabel>
  <UploadValue>{(state) => state.text}</UploadValue>
  <UploadTrack>
    <UploadBar />
  </UploadTrack>
</Upload>
```

`ProgressValue` shows the formatted value when it has no children. A part from `createParts` renders only its children, so pass `(state) => state.text` to show the same text.

Each part keeps the behavior, state and data attributes of its ready-made counterpart: the root is the `progressbar`, and the indicator sets its width from the value. See [Rendering](/docs/react/rendering) and [Custom Parts](/docs/react/custom-parts) for more.

## Indeterminate

Leave out `value` when you do not know how much work is complete. Every part gets `data-indeterminate`, and the root has no `aria-valuenow`.

The indicator has no inline width in this state. This example sweeps a short highlight across the track, and shows a still, full-width fill when reduced motion is on.

```tsx title="indeterminate.tsx"
import {
  Progress,
  ProgressIndicator,
  ProgressLabel,
  ProgressTrack,
} from "@ui-sdk/react/progress"

function Example() {
  return (
    <Progress value={null}>
      <ProgressLabel>Connecting to server</ProgressLabel>
      <ProgressTrack>
        <ProgressIndicator />
      </ProgressTrack>
    </Progress>
  )
}

export { Example }
```

Read the Connecting to server bar. It shows an ongoing task without announcing a percentage.

## Changing the Value

Pass the latest `value` as your task progresses. The parts get `data-progressing` while the value is below `max`, and `data-complete` when it reaches the end.

```tsx title="controlled.tsx"
"use client"

import {
  Progress,
  ProgressIndicator,
  ProgressLabel,
  ProgressTrack,
  ProgressValue,
} from "@ui-sdk/react/progress"
import * as React from "react"
import { useLog } from "./log"

const total = 5

function Example() {
  const log = useLog()
  const [uploaded, setUploaded] = React.useState(1)

  function uploadNext() {
    if (uploaded >= total) {
      return
    }
    setUploaded(uploaded + 1)
    log(`Uploaded ${uploaded + 1} of ${total} photos`)
  }

  function reset() {
    setUploaded(0)
    log("Reset to 0 photos")
  }

  return (
    <div data-slot="stack">
      <div data-slot="controls">
        <button
          type="button"
          aria-disabled={uploaded >= total}
          onClick={uploadNext}
        >
          Upload Next
        </button>
        <button type="button" onClick={reset}>
          Reset
        </button>
      </div>
      <Progress value={(uploaded / total) * 100}>
        <ProgressLabel>Uploading photos</ProgressLabel>
        <ProgressValue />
        <ProgressTrack>
          <ProgressIndicator />
        </ProgressTrack>
      </Progress>
    </div>
  )
}

export { Example }
```

Click Upload Next to add one photo, or 20%, and watch the console count them. At 100%, the button stops advancing the bar. Click Reset to start at 0%.

Progress displays your state; it has no `onValueChange` callback.

## Bounds

`min` and `max` default to 0 and 100. A value outside that range is clamped for the fill, the percentage and `aria-valuenow`, but the state's `value` and a format other than percent keep it as you passed it. A value of 3 between 1 and 5 fills half the track.

```tsx title="min-max.tsx"
import {
  Progress,
  ProgressIndicator,
  ProgressLabel,
  ProgressTrack,
  ProgressValue,
} from "@ui-sdk/react/progress"

function Example() {
  return (
    <Progress value={3} min={1} max={5}>
      <ProgressLabel>Account setup, step 3 of 5</ProgressLabel>
      <ProgressValue />
      <ProgressTrack>
        <ProgressIndicator />
      </ProgressTrack>
    </Progress>
  )
}

export { Example }
```

Compare step 3 of 5 with the fill. Because the range starts at 1, the value is halfway through the range.

## Format and Locale

Pass `Intl.NumberFormat` options to `format` for units or decimal places. A function can return custom text, such as the time remaining.

```tsx title="format.tsx"
import {
  Progress,
  ProgressIndicator,
  ProgressLabel,
  ProgressTrack,
  ProgressValue,
} from "@ui-sdk/react/progress"

const bars = [
  {
    label: "Download",
    value: 120,
    max: 250,
    format: { style: "unit", unit: "gigabyte" },
  },
  {
    label: "Video render",
    value: 87.25,
    format: { style: "percent", maximumFractionDigits: 1 },
  },
  {
    label: "Backup",
    value: 45,
    max: 60,
    format: (minutes: number) => `${60 - minutes} min left`,
  },
  { label: "Synchronisierung", value: 40, locale: "de-DE" },
] satisfies {
  label: string
  value: number
  max?: number
  format?: Intl.NumberFormatOptions | ((value: number) => string)
  locale?: string
}[]

function Example() {
  return (
    <div data-slot="stack">
      {bars.map(({ label, ...options }) => (
        <Progress key={label} {...options}>
          <ProgressLabel>{label}</ProgressLabel>
          <ProgressValue />
          <ProgressTrack>
            <ProgressIndicator />
          </ProgressTrack>
        </Progress>
      ))}
    </div>
  )
}

export { Example }
```

Compare the progress readings. They show downloaded data, a precise percentage, time remaining, and a localized percentage.

A percent format reports the value's position between `min` and `max`. Other formats use the value itself.

`locale` controls digits and separators. If you omit it, the component reads the page's language after it mounts, with the browser's language as a fallback. The initial server and client render use English.

Set `dir="rtl"` on the surrounding content to fill the track from the right.

## Value Label

Use `getValueLabel` to give screen readers more context than the visible number. Its details include `formatted`, `percent`, `min`, and `max`. Handle a `null` value when the task can be indeterminate; `percent` is also `null` and `formatted` is empty then.

```tsx title="value-label.tsx"
import {
  Progress,
  ProgressIndicator,
  ProgressLabel,
  ProgressTrack,
  ProgressValue,
} from "@ui-sdk/react/progress"

function Example() {
  return (
    <Progress
      value={3}
      max={12}
      getValueLabel={(value, details) =>
        `${value} of ${details.max} files, ${details.formatted}`
      }
    >
      <ProgressLabel>Copying files</ProgressLabel>
      <ProgressValue>3 of 12</ProgressValue>
      <ProgressTrack>
        <ProgressIndicator />
      </ProgressTrack>
    </Progress>
  )
}

export { Example }
```

Read Copying files with a screen reader. It announces 3 of 12 files and 25%, while the visible value stays compact.

Use [Meter](/docs/react/components/meter) for a reading such as storage used, rather than a task that will finish.

## Custom Rendering

See [Parts and Composition](/docs/react/parts-and-composition) for changing a part's element or reading its state. Use `format` for text that should be shared by the visible value and screen readers.

## Styling

Give the track a height, background, and width. The indicator sets its width as an inline percentage of the track. Style `data-indeterminate` for a task whose progress is unknown, since the indicator has no width then, and `data-complete` once the task finishes. Both styling options are shown in each example's Code tab.

Each part has a `data-slot`, such as `progress-indicator`, and its state attributes are listed under [Data Attributes](#data-attributes).

### Progress
The root exposes a CSS variable for positioning other content alongside the reading.

- `--progress-value`: Where the value sits between `min` and `max`, as a percentage, like 40%. Unset while indeterminate.

## Data Attributes

### Progress
`[data-slot="progress"]`

- `data-indeterminate`: Present while the value is null: the task is under way, but how far is unknown.
- `data-progressing`: Present while the value is below `max`.
- `data-complete`: Present once the value reaches `max`.

### ProgressLabel
`[data-slot="progress-label"]`

- `data-indeterminate`: Present while the value is null: the task is under way, but how far is unknown.
- `data-progressing`: Present while the value is below `max`.
- `data-complete`: Present once the value reaches `max`.

### ProgressValue
`[data-slot="progress-value"]`

- `data-indeterminate`: Present while the value is null: the task is under way, but how far is unknown.
- `data-progressing`: Present while the value is below `max`.
- `data-complete`: Present once the value reaches `max`.

### ProgressTrack
`[data-slot="progress-track"]`

- `data-indeterminate`: Present while the value is null: the task is under way, but how far is unknown.
- `data-progressing`: Present while the value is below `max`.
- `data-complete`: Present once the value reaches `max`.

### ProgressIndicator
`[data-slot="progress-indicator"]`

- `data-indeterminate`: Present while the value is null: the task is under way, but how far is unknown.
- `data-progressing`: Present while the value is below `max`.
- `data-complete`: Present once the value reaches `max`.

## API Reference

Props are the same as below, as React props.

### Progress

- `min?` (`number`): The lowest value.
- `max?` (`number`): The highest value.
- `format?` (`NumberFormat`): How the value reads, for screen readers and the Value part: `Intl.NumberFormat` options, or a function of the value. A percent style shows where the value sits between `min` and `max`; any other style shows the value itself, like `{ style: "unit", unit: "gigabyte" }`.
- `locale?` (`string`): The locale the value is formatted in. Defaults to the page's `lang`, or the browser's language without one, once the page is interactive. Server markup uses English until then, so it never disagrees with the client.
- `getValueLabel?` (`((value: number | null, details: GaugeLabelDetails<number | null>) => string)`): The text screen readers announce for the value, when the formatted value says too little, like "3 of 12 files". It receives the value, null while a progress bar is indeterminate, and details: the `formatted` value, its `percent`, `min` and `max`.
- `value?` (`number | null`): How far the task has come, between `min` and `max`. Null means it's under way but how far is unknown, and the bar is indeterminate.
- `debug?` (`boolean`): Logs every state change with its reason to the console, in development builds.

### State

What render functions, state-based class names and slots receive. Every part gets the same state.

- `value` (`number | null`): The value, or null while indeterminate.
- `percent` (`number | null`): Where the value sits between `min` and `max`, from 0 to 100, or null while indeterminate.
- `status` (`ProgressStatus`): Whether the progress is unknown, under way, or done.

`ProgressValue` adds the formatted text:

- `value` (`number | null`): The value, or null while indeterminate.
- `percent` (`number | null`): Where the value sits between `min` and `max`, from 0 to 100, or null while indeterminate.
- `status` (`ProgressStatus`): Whether the progress is unknown, under way, or done.
- `text` (`string`): The formatted value, like "40%". Empty while indeterminate.

## Accessibility

Name the component with `ProgressLabel` or `aria-label`. It exposes the range and formatted value through the `progressbar` role. Use `getValueLabel` when that value needs more explanation.

### Tested Behavior

Every line below is an automated test.

- A progress bar is named by its label and reads its value.
- The value part shows the formatted value.
- The indicator is as wide as the value.
- A new value updates the bar.
- Every part says whether the task is under way, done, or unknown.
- An indeterminate bar has no value.
- A unit format reads the value itself.
- A value label replaces the formatted value for screen readers.
- A value above the maximum reads as the maximum.

Runs in React, Vue and web components.