# Pagination

> Buttons for moving between pages, with an ellipsis for the ones it doesn't show.

`<slab-pagination>` · Navigation · built on `<nav> + <button>s`

## Install

```sh
pnpm add slab-elements lit
```

## Usage

```html
<script type="module">
  import 'slab-elements/pagination.js';
</script>

<slab-pagination page="1" total="20"></slab-pagination>
```

## Example

Here's a styled version, `<slab-styled-pagination>`. It's not in the package — it's an example of what you can build with the headless element. Copy it and make it yours at the bottom of this page.

```html
<slab-styled-pagination label="Pour log" page="5" total="12"></slab-styled-pagination>
```

Swap `slab-styled-` for `slab-` in that markup and you've got the same example as it ships: the headless elements with no CSS at all. That's your starting point.

When it dispatches "change", read the new `page` and navigate.

## Behavior

Pagination with no visual styles: a `<nav>` around a list of `<button>`s, one for each page shown, between a previous and a next one.

The first and last pages are always shown, and so are `siblings` pages either side of the current one. The pages between those are an ellipsis, so there are always as many items, and the buttons don't move as the page changes.

The current page's button has `aria-current="page"`. Previous and Next are `aria-disabled` rather than `disabled` at either end, so focus stays on them when they reach it. Clicking a page sets `page` and dispatches "change".

Style it through its parts and `:state(first)` and `:state(last)`, which are set on the first and last pages. The current page's button is also `::part(current)`.

## API

### `<slab-pagination>`

#### Attributes

| Name | Type | Default | Description |
| --- | --- | --- | --- |
| `total` (required) | `number` |  | How many pages there are. |
| `label` | `string` |  | Names the navigation. "Pagination" when unset. |
| `next-label` | `string` |  | The next button's text and so its accessible name. "Next" when unset. |
| `page` | `number` | `1` | The current page, from 1 to `total`. |
| `previous-label` | `string` |  | The previous button's text and so its accessible name. "Previous" when unset. |
| `siblings` | `number` | `1` | How many pages are shown either side of the current one. |
| `version` | `string` |  |  |

#### Properties

| Name | Type | Description |
| --- | --- | --- |
| `pageLabel` | `(page: number) => string` | Names each page's button, which shows only the number, from that number. "Page" and the number when unset. |

#### Events

| Name | Type | Description |
| --- | --- | --- |
| `change` | `Event` |  |

#### CSS parts

| Name | Description |
| --- | --- |
| `current` | The current page's button |
| `ellipsis` | In place of the pages that aren't shown |
| `item` | Each button's or ellipsis's list item |
| `list` | The buttons |
| `nav` | The navigation |
| `next` | The button to the next page |
| `page` | Each page's button |
| `previous` | The button to the previous page |

## Copy and own it

`<slab-styled-pagination>` isn't in the package. It's an example — copy it into your project and change whatever you want. Under the hood, it's just the headless element, subclassed, with `styles` set. That's it. Keyboard, focus, ARIA, forms, and events all come from the headless element, and the styles only reach in through `::part()` and `:state()`, same as yours would.

To use it, copy these files, swap the tag in `@customElement()` for one of your own, and import it. `tokens.styles.ts` holds the colors and fonts every styled example shares, so you only need it once.

### TypeScript

These files are TypeScript, and `@customElement()` is one of Lit's decorators (TypeScript's experimental flavor). You'll need two options in your tsconfig, per [Lit's docs](https://lit.dev/docs/components/decorators/#decorators-typescript): `experimentalDecorators` to compile them, and `useDefineForClassFields` turned off so class fields don't stomp on the accessors Lit sets up.

```json
{
  "compilerOptions": {
    "experimentalDecorators": true,
    "useDefineForClassFields": false
  }
}
```

Using plain JavaScript? Drop the types and register the class with `customElements.define()` instead of the decorator.

### pagination.ts

```ts
import { customElement } from 'lit/decorators.js';
import Pagination from 'slab-elements/pagination.js';
import styles from './pagination.styles.js';
import tokens from './tokens.styles.js';

declare global {
  interface HTMLElementTagNameMap {
    'slab-styled-pagination': StyledPagination;
  }
}

/**
 * Pagination, styled: a course of square buttons, with the current page in
 * ink.
 */
@customElement('slab-styled-pagination')
export default class StyledPagination extends Pagination {
  static override styles = [tokens, styles];
}
```

### pagination.styles.ts

```ts
import { css } from 'lit';

/*
  At the first and last pages, Previous and Next are "aria-disabled" rather
  than disabled, so they keep focus. They're styled from Pagination's
  ":state(first)" and ":state(last)".
*/
export default css`
  [part~='list'] {
    align-items: center;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    list-style: none;
    margin: 0;
    padding: 0;
  }

  [part~='page'],
  [part~='previous'],
  [part~='next'] {
    background-color: var(--paper);
    block-size: 2.5rem;
    border: var(--border);
    box-shadow: 3px 3px 0 var(--ink);
    color: var(--ink);
    cursor: pointer;
    font-family: var(--font-display);
    font-size: 1rem;
    font-weight: 600;
    min-inline-size: 2.5rem;
    padding: 0 0.75rem;
    transition:
      background-color 100ms,
      box-shadow 100ms;

    &:hover {
      background-color: var(--chalk);
    }

    &:active {
      box-shadow: 1px 1px 0 var(--ink);
    }

    &:focus-visible {
      outline: 3px solid var(--ember);
      outline-offset: 3px;
    }
  }

  [part~='current'] {
    background-color: var(--ink);
    box-shadow: 3px 3px 0 var(--ember);
    color: var(--paper);

    &:hover {
      background-color: var(--ink);
    }
  }

  [part~='ellipsis'] {
    color: var(--ash);
    font-family: var(--font-mono);
    padding-inline: 0.25rem;
  }

  :host(:state(first)) [part~='previous'],
  :host(:state(last)) [part~='next'] {
    background-color: var(--chalk);
    border-style: dashed;
    box-shadow: none;
    color: var(--ash);
    cursor: not-allowed;
  }

  @media (prefers-reduced-motion: reduce) {
    [part~='page'],
    [part~='previous'],
    [part~='next'] {
      transition: none;
    }
  }
`;
```

### tokens.styles.ts

```ts
import { css } from 'lit';

/*
  The styled components' palette and type, taken from the logo: ink for the
  courses, ember for the base, paper behind them.

  Each is a short alias for a "--slab-styled-*" property, with the default as
  its fallback. Retheming is "--slab-styled-ember" and the rest on ":root",
  which every shadow root inherits. Were the defaults declared under those
  names here instead, each host's own declaration would shadow the page's.

  Each default is "light-dark()", so the components follow the page's
  "color-scheme": "dark" for dark, "light" for light, and "light dark" to
  follow the operating system. Ink and paper trade places in the dark, so
  ink is always the text and paper always what's behind it. Contrast is given
  as light, then dark.
*/
export default css`
  :host {
    /* Secondary text. 6.8:1 and 6.9:1 on paper. */
    --ash: var(--slab-styled-ash, light-dark(#5e5a55, #a8a19a));
    --border: 2px solid var(--ink);

    /* Behind disabled and read-only controls, and hovered rows. */
    --chalk: var(--slab-styled-chalk, light-dark(#f4f1ec, #2b2926));

    /*
      The logo's orange, brighter in the dark. 4.25:1 and 5.2:1 on paper is
      enough for borders, fills and large text, but not always for small text,
      which takes "--ember-deep".
    */
    --ember: var(--slab-styled-ember, light-dark(#d9492a, #ec5f3b));

    /*
      Orange for small text on paper, and for paper text on it. 5.7:1 and
      7.4:1.
    */
    --ember-deep: var(--slab-styled-ember-deep, light-dark(#b3381a, #ff8566));
    --font-body: var(
      --slab-styled-font-body,
      'IBM Plex Sans',
      system-ui,
      sans-serif
    );
    --font-display: var(
      --slab-styled-font-display,
      'Zilla Slab',
      rockwell,
      'Roboto Slab',
      serif
    );
    --font-mono: var(
      --slab-styled-font-mono,
      'IBM Plex Mono',
      ui-monospace,
      monospace
    );
    --ink: var(--slab-styled-ink, light-dark(#1c1c1c, #f4f1ec));
    --paper: var(--slab-styled-paper, light-dark(#fff, #1a1918));

    /* The hard, offset shadow a raised surface casts. */
    --shadow: 4px 4px 0 var(--ink);
  }
`;
```