mdast-util-gfm-table

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mdast extensions to parse and serialize GFM tables.

Contents

What is this?

This package contains two extensions that add support for GFM table syntax in
markdown to mdast.
These extensions plug into
mdast-util-from-markdown (to support parsing
tables in markdown into a syntax tree) and
mdast-util-to-markdown (to support serializing
tables in syntax trees to markdown).

When to use this

You can use these extensions when you are working with
mdast-util-from-markdown and mdast-util-to-markdown already.

When working with mdast-util-from-markdown, you must combine this package
with micromark-extension-gfm-table.

When you don’t need a syntax tree, you can use micromark
directly with micromark-extension-gfm-table.

When you are working with syntax trees and want all of GFM, use
mdast-util-gfm instead.

All these packages are used remark-gfm, which
focusses on making it easier to transform content by abstracting these
internals away.

This utility does not handle how markdown is turned to HTML.
That’s done by mdast-util-to-hast.

Install

This package is ESM only.
In Node.js (version 16+), install with npm:

npm install mdast-util-gfm-table

In Deno with esm.sh:

import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'https://esm.sh/mdast-util-gfm-table@2'

In browsers with esm.sh:

<script type="module">
  import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'https://esm.sh/mdast-util-gfm-table@2?bundle'
</script>

Use

Say our document example.md contains:

| a | b | c | d |
| - | :- | -: | :-: |
| e | f |
| g | h | i | j | k |

…and our module example.js looks as follows:

import fs from 'node:fs/promises'
import {gfmTable} from 'micromark-extension-gfm-table'
import {fromMarkdown} from 'mdast-util-from-markdown'
import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'mdast-util-gfm-table'
import {toMarkdown} from 'mdast-util-to-markdown'

const doc = await fs.readFile('example.md')

const tree = fromMarkdown(doc, {
  extensions: [gfmTable()],
  mdastExtensions: [gfmTableFromMarkdown()]
})

console.log(tree)

const out = toMarkdown(tree, {extensions: [gfmTableToMarkdown()]})

console.log(out)

…now running node example.js yields (positional info removed for brevity):

{
  type: 'root',
  children: [
    {
      type: 'table',
      align: [null, 'left', 'right', 'center'],
      children: [
        {
          type: 'tableRow',
          children: [
            {type: 'tableCell', children: [{type: 'text', value: 'a'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'b'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'c'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'd'}]}
          ]
        },
        {
          type: 'tableRow',
          children: [
            {type: 'tableCell', children: [{type: 'text', value: 'e'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'f'}]}
          ]
        },
        {
          type: 'tableRow',
          children: [
            {type: 'tableCell', children: [{type: 'text', value: 'g'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'h'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'i'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'j'}]},
            {type: 'tableCell', children: [{type: 'text', value: 'k'}]}
          ]
        }
      ]
    }
  ]
}

| a | b  |  c |  d  |   |
| - | :- | -: | :-: | - |
| e | f  |    |     |   |
| g | h  |  i |  j  | k |

API

This package exports the identifiers
gfmTableFromMarkdown and
gfmTableToMarkdown.
There is no default export.

gfmTableFromMarkdown

Create an extension for mdast-util-from-markdown
to enable GFM tables in markdown.

Returns

Extension for mdast-util-from-markdown to enable GFM tables
(FromMarkdownExtension).

gfmTableToMarkdown(options?)

Create an extension for mdast-util-to-markdown to
enable GFM tables in markdown.

Parameters
  • options (Options, optional)
    — configuration
Returns

Extension for mdast-util-to-markdown to enable GFM tables
(ToMarkdownExtension).

Options

Configuration (TypeScript type).

Fields
  • tableCellPadding (boolean, default: true)
    — whether to add a space of padding between delimiters and cells
  • tablePipeAlign (boolean, default: true)
    — whether to align the delimiters
  • stringLength (((value: string) => number), default: s => s.length)
    — function to detect the length of table cell content, used when aligning
    the delimiters between cells

Examples

Example: stringLength

It’s possible to align tables based on the visual width of cells.
First, let’s show the problem:

import {gfmTable} from 'micromark-extension-gfm-table'
import {fromMarkdown} from 'mdast-util-from-markdown'
import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'mdast-util-gfm-table'
import {toMarkdown} from 'mdast-util-to-markdown'

const doc = `| Alpha | Bravo |
| - | - |
| 中文 | Charlie |
| 👩 | Delta |`

const tree = fromMarkdown(doc, {
  extensions: [gfmTable],
  mdastExtensions: [gfmTableFromMarkdown]
})

console.log(toMarkdown(tree, {extensions: [gfmTableToMarkdown()]}))

The above code shows how these utilities can be used to format markdown.
The output is as follows:

| Alpha    | Bravo   |
| -------- | ------- |
| 中文       | Charlie |
| 👩 | Delta   |

To improve the alignment of these full-width characters and emoji, pass a
stringLength function that calculates the visual width of cells.
One such algorithm is string-width.
It can be used like so:

@@ -2,6 +2,7 @@ import {gfmTable} from 'micromark-extension-gfm-table'
 import {fromMarkdown} from 'mdast-util-from-markdown'
 import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'mdast-util-gfm-table'
 import {toMarkdown} from 'mdast-util-to-markdown'
+import stringWidth from 'string-width'

 const doc = `| Alpha | Bravo |
 | - | - |
@@ -13,4 +14,8 @@ const tree = fromMarkdown(doc, {
   mdastExtensions: [gfmTableFromMarkdown()]
 })

-console.log(toMarkdown(tree, {extensions: [gfmTableToMarkdown()]}))
+console.log(
+  toMarkdown(tree, {
+    extensions: [gfmTableToMarkdown({stringLength: stringWidth})]
+  })
+)

The output of our code with these changes is as follows:

| Alpha | Bravo   |
| ----- | ------- |
| 中文  | Charlie |
| 👩    | Delta   |

HTML

This utility does not handle how markdown is turned to HTML.
That’s done by mdast-util-to-hast.

Syntax

See Syntax in micromark-extension-gfm-table.

Syntax tree

The following interfaces are added to mdast by this utility.

Nodes

Table

interface Table <: Parent {
  type: 'table'
  align: [alignType]?
  children: [TableContent]
}

Table (Parent) represents two-dimensional data.

Table can be used where flow content is expected.
Its content model is table content.

The head of the node represents the labels of the columns.

An align field can be present.
If present, it must be a list of alignTypes.
It represents how cells in columns are aligned.

For example, the following markdown:

| foo | bar |
| :-- | :-: |
| baz | qux |

Yields:

{
  type: 'table',
  align: ['left', 'center'],
  children: [
    {
      type: 'tableRow',
      children: [
        {
          type: 'tableCell',
          children: [{type: 'text', value: 'foo'}]
        },
        {
          type: 'tableCell',
          children: [{type: 'text', value: 'bar'}]
        }
      ]
    },
    {
      type: 'tableRow',
      children: [
        {
          type: 'tableCell',
          children: [{type: 'text', value: 'baz'}]
        },
        {
          type: 'tableCell',
          children: [{type: 'text', value: 'qux'}]
        }
      ]
    }
  ]
}

TableRow

interface TableRow <: Parent {
  type: "tableRow"
  children: [RowContent]
}

TableRow (Parent) represents a row of cells in a table.

TableRow can be used where table content is
expected.
Its content model is row content.

If the node is a head, it represents the labels of the columns
for its parent Table.

For an example, see Table.

TableCell

interface TableCell <: Parent {
  type: "tableCell"
  children: [PhrasingContent]
}

TableCell (Parent) represents a header cell in a
Table, if its parent is a head, or a data
cell otherwise.

TableCell can be used where row content is expected.
Its content model is phrasing content excluding
Break nodes.

For an example, see Table.

Enumeration

alignType

enum alignType {
  'center' | 'left' | 'right' | null
}

alignType represents how phrasing content is aligned
([CSSTEXT]).

  • 'left': See the left value of the text-align CSS
    property
  • 'right': See the right value of the text-align
    CSS property
  • 'center': See the center value of the text-align
    CSS property
  • null: phrasing content is aligned as defined by the host environment

Content model

FlowContent (GFM table)

type FlowContentGfm = Table | FlowContent

TableContent

type TableContent = TableRow

Table content represent the rows in a table.

RowContent

type RowContent = TableCell

Row content represent the cells in a row.

Types

This package is fully typed with TypeScript.
It exports the additional type Options.

The Table, TableRow, and TableCell types of the mdast nodes are exposed
from @types/mdast.

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, mdast-util-gfm-table@^2,
compatible with Node.js 16.

This utility works with mdast-util-from-markdown version 2+ and
mdast-util-to-markdown version 2+.

Contribute

See contributing.md in syntax-tree/.github for
ways to get started.
See support.md for ways to get help.

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

License

MIT © Titus Wormer

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