remark-lint-table-pipe-alignment/readme.md

remark-lint rule to warn when table pipes are not aligned

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# remark-lint-table-pipe-alignment

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[`remark-lint`][github-remark-lint] rule to warn when GFM table cells are aligned inconsistently.

## Contents

* [What is this?](#what-is-this)
* [When should I use this?](#when-should-i-use-this)
* [Presets](#presets)
* [Install](#install)
* [Use](#use)
* [API](#api)
  * [`unified().use(remarkLintTablePipeAlignment[, options])`](#unifieduseremarklinttablepipealignment-options)
  * [`Options`](#options)
* [Recommendation](#recommendation)
* [Fix](#fix)
* [Examples](#examples)
* [Compatibility](#compatibility)
* [Contribute](#contribute)
* [License](#license)

## What is this?

This package checks table cell dividers are aligned.
Tables are a GFM feature enabled with [`remark-gfm`][github-remark-gfm].

## When should I use this?

You can use this package to check that tables are consistent.

## Presets

This plugin is included in the following presets:

| Preset | Options |
| - | - |
| [`remark-preset-lint-markdown-style-guide`](https://github.com/remarkjs/remark-lint/tree/main/packages/remark-preset-lint-markdown-style-guide) | |

## Install

This package is [ESM only][github-gist-esm].
In Node.js (version 16+),
install with [npm][npm-install]:

```sh
npm install remark-lint-table-pipe-alignment
```

In Deno with [`esm.sh`][esm-sh]:

```js
import remarkLintTablePipeAlignment from 'https://esm.sh/remark-lint-table-pipe-alignment@4'
```

In browsers with [`esm.sh`][esm-sh]:

```html
<script type="module">
  import remarkLintTablePipeAlignment from 'https://esm.sh/remark-lint-table-pipe-alignment@4?bundle'
</script>
```

## Use

On the API:

```js
import remarkLint from 'remark-lint'
import remarkLintTablePipeAlignment from 'remark-lint-table-pipe-alignment'
import remarkParse from 'remark-parse'
import remarkStringify from 'remark-stringify'
import {read} from 'to-vfile'
import {unified} from 'unified'
import {reporter} from 'vfile-reporter'

const file = await read('example.md')

await unified()
  .use(remarkParse)
  .use(remarkLint)
  .use(remarkLintTablePipeAlignment)
  .use(remarkStringify)
  .process(file)

console.error(reporter(file))
```

On the CLI:

```sh
remark --frail --use remark-lint --use remark-lint-table-pipe-alignment .
```

On the CLI in a config file (here a `package.json`):

```diff
 …
 "remarkConfig": {
   "plugins": [
     …
     "remark-lint",
+    "remark-lint-table-pipe-alignment",
     …
   ]
 }
 …
```

## API

This package exports no identifiers.
It exports the [TypeScript][typescript] type
[`Options`][api-options].
The default export is
[`remarkLintTablePipeAlignment`][api-remark-lint-table-pipe-alignment].

### `unified().use(remarkLintTablePipeAlignment[, options])`

Warn when GFM table cells are aligned inconsistently.

###### Parameters

* `options` ([`Options`][api-options], optional)
  — configuration

###### Returns

Transform ([`Transformer` from `unified`][github-unified-transformer]).

### `Options`

Configuration (TypeScript type).

###### Properties

* `stringLength` (`(value: string) => number`, optional)
  — function to detect cell size

## Recommendation

While aligning table dividers improves their legibility,
it is somewhat hard to maintain manually,
especially for tables with many rows.

## Fix

[`remark-stringify`][github-remark-stringify] with
[`remark-gfm`][github-remark-gfm] aligns table cell dividers by default.
Pass `tablePipeAlign: false` to use a more compact style.

Aligning perfectly in all cases is not possible because whether characters
look aligned or not depends on where the markup is shown.
Some characters (such as emoji or Chinese characters) show smaller or bigger
in different places.
You can pass a `stringLength` function to `remark-gfm`,
to align better for your use case,
in which case this rule must be configured with the same `stringLength`.

## Examples

##### `ok.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
This rule is only about the alignment of pipes across rows:

| Planet  | Mean anomaly (°) |
| ------- | ---------------: |
| Mercury |          174 796 |

|Planet|Mean anomaly (°)|
|------|---------------:|
|Venus |         50 115 |
```

###### Out

No messages.

##### `not-ok.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Planet | Mean anomaly (°) |
| - | -: |
| Mercury | 174 796 |
```

###### Out

```text
1:10: Unexpected unaligned cell, expected aligned pipes, add `1` space
2:5: Unexpected unaligned cell, expected aligned pipes, add `6` spaces (or add `-` to pad alignment row cells)
2:7: Unexpected unaligned cell, expected aligned pipes, add `14` spaces (or add `-` to pad alignment row cells)
3:13: Unexpected unaligned cell, expected aligned pipes, add `9` spaces
```

##### `empty.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
|         | Satellites |     |
| ------- | ---------- | --- |
| Mercury |            |     |

| aaa | bbb | ccc | ddd |
| --- | :-- | :-: | --: |
|     |     |     |     |
```

###### Out

No messages.

##### `aligned-pipes-but-weird-content.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Planet | Moon | Mercury | Venus | Sun | Mars | Jupiter | Saturn |
| ------ | ---- | :------ | :---- | --: | ---: | :-----: | :----: |
| Symbol |    ☾ | ☿       |   ♀   | ☉   |   ♂  | ♃       |      ♄ |
```

###### Out

No messages.

##### `missing-cells.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Planet  | Symbol | Satellites |
| ------- | ------ | ---------- |
| Mercury |
| Venus   | ♀      |
| Earth   | ♁      | 1          |
| Mars    | ♂      | 2          | 19 412 |
```

###### Out

No messages.

##### `alignment.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Planet | Symbol | Satellites | Mean anomaly (°) |
| - | :- | :-: | -: |
| Mercury | ☿ | None | 174 796 |
```

###### Out

```text
1:10: Unexpected unaligned cell, expected aligned pipes, add `1` space
2:5: Unexpected unaligned cell, expected aligned pipes, add `6` spaces (or add `-` to pad alignment row cells)
2:10: Unexpected unaligned cell, expected aligned pipes, add `4` spaces (or add `-` to pad alignment row cells)
2:12: Unexpected unaligned cell, expected aligned pipes, add `4` spaces (or add `-` to pad alignment row cells)
2:16: Unexpected unaligned cell, expected aligned pipes, add `3` spaces (or add `-` to pad alignment row cells)
2:18: Unexpected unaligned cell, expected aligned pipes, add `14` spaces (or add `-` to pad alignment row cells)
3:15: Unexpected unaligned cell, expected aligned pipes, add `5` spaces
3:17: Unexpected unaligned cell, expected aligned pipes, add `3` spaces
3:22: Unexpected unaligned cell, expected aligned pipes, add `3` spaces
3:24: Unexpected unaligned cell, expected aligned pipes, add `9` spaces
```

##### `missing-fences.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
Planet | Satellites
-: | -
Mercury | ☿
```

###### Out

```text
1:1: Unexpected unaligned cell, expected aligned pipes, add `1` space
2:1: Unexpected unaligned cell, expected aligned pipes, add `5` spaces (or add `-` to pad alignment row cells)
```

##### `trailing-spaces.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Planet |␠␠
| -: |␠
```

###### Out

```text
2:3: Unexpected unaligned cell, expected aligned pipes, add `4` spaces (or add `-` to pad alignment row cells)
```

##### `nothing.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
||||
|-|-|-|
```

###### Out

```text
1:2: Unexpected unaligned cell, expected aligned pipes, add `1` space
1:3: Unexpected unaligned cell, expected aligned pipes, add `1` space
1:4: Unexpected unaligned cell, expected aligned pipes, add `1` space
```

##### `more-weirdness.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
Mercury
|-

Venus
-|
```

###### Out

```text
5:2: Unexpected unaligned cell, expected aligned pipes, add `4` spaces (or add `-` to pad alignment row cells)
```

##### `containers.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
> | Mercury|
> | - |

* | Venus|
  | - |

> * > | Earth|
>   > | - |
```

###### Out

```text
2:5: Unexpected unaligned cell, expected aligned pipes, add `5` spaces (or add `-` to pad alignment row cells)
5:5: Unexpected unaligned cell, expected aligned pipes, add `3` spaces (or add `-` to pad alignment row cells)
8:5: Unexpected unaligned cell, expected aligned pipes, add `3` spaces (or add `-` to pad alignment row cells)
```

##### `windows.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Mercury|␍␊| --- |␍␊| None |
```

###### Out

```text
2:7: Unexpected unaligned cell, expected aligned pipes, add `3` spaces (or add `-` to pad alignment row cells)
3:8: Unexpected unaligned cell, expected aligned pipes, add `2` spaces
```

##### `string-length-default.md`

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Alpha | Bravo   |
| ----- | ------- |
| 冥王星   | Charlie |
| 🪐    | Delta   |
```

###### Out

No messages.

##### `string-length-custom.md`

When configured with `{ stringLength: [Function: stringWidth] }`.

###### In

> 👉 **Note**: this example uses
> GFM ([`remark-gfm`][github-remark-gfm]).

```markdown
| Alpha  | Bravo   |
| ------ | ------- |
| 冥王星 | Charlie |
| 🪐     | Delta   |
```

###### Out

No messages.

## Compatibility

Projects maintained by the unified collective are compatible with maintained
versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of
Node.
This means we try to keep the current release line,
`remark-lint-table-pipe-alignment@4`,
compatible with Node.js 16.

## Contribute

See [`contributing.md`][github-dotfiles-contributing] in [`remarkjs/.github`][github-dotfiles-health] for ways
to get started.
See [`support.md`][github-dotfiles-support] for ways to get help.

This project has a [code of conduct][github-dotfiles-coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.

## License

[MIT][file-license] © [Titus Wormer][author]

[api-options]: #options

[api-remark-lint-table-pipe-alignment]: #unifieduseremarklinttablepipealignment-options

[author]: https://wooorm.com

[badge-build-image]: https://github.com/remarkjs/remark-lint/workflows/main/badge.svg

[badge-build-url]: https://github.com/remarkjs/remark-lint/actions

[badge-chat-image]: https://img.shields.io/badge/chat-discussions-success.svg

[badge-chat-url]: https://github.com/remarkjs/remark/discussions

[badge-coverage-image]: https://img.shields.io/codecov/c/github/remarkjs/remark-lint.svg

[badge-coverage-url]: https://codecov.io/github/remarkjs/remark-lint

[badge-downloads-image]: https://img.shields.io/npm/dm/remark-lint-table-pipe-alignment.svg

[badge-downloads-url]: https://www.npmjs.com/package/remark-lint-table-pipe-alignment

[badge-funding-backers-image]: https://opencollective.com/unified/backers/badge.svg

[badge-funding-sponsors-image]: https://opencollective.com/unified/sponsors/badge.svg

[badge-funding-url]: https://opencollective.com/unified

[badge-size-image]: https://img.shields.io/bundlejs/size/remark-lint-table-pipe-alignment

[badge-size-url]: https://bundlejs.com/?q=remark-lint-table-pipe-alignment

[esm-sh]: https://esm.sh

[file-license]: https://github.com/remarkjs/remark-lint/blob/main/license

[github-dotfiles-coc]: https://github.com/remarkjs/.github/blob/main/code-of-conduct.md

[github-dotfiles-contributing]: https://github.com/remarkjs/.github/blob/main/contributing.md

[github-dotfiles-health]: https://github.com/remarkjs/.github

[github-dotfiles-support]: https://github.com/remarkjs/.github/blob/main/support.md

[github-gist-esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[github-remark-gfm]: https://github.com/remarkjs/remark-gfm

[github-remark-lint]: https://github.com/remarkjs/remark-lint

[github-remark-stringify]: https://github.com/remarkjs/remark/tree/main/packages/remark-stringify

[github-unified-transformer]: https://github.com/unifiedjs/unified#transformer

[npm-install]: https://docs.npmjs.com/cli/install

[typescript]: https://www.typescriptlang.org