mdast-util-gfm-table

What is mdast-util-gfm-table?

The mdast-util-gfm-table package is a utility to support GitHub Flavored Markdown (GFM) tables in mdast, which is a syntax tree format for Markdown. It allows users to parse and serialize tables in Markdown files following the GFM specification.

What are mdast-util-gfm-table's main functionalities?

Parsing GFM tables

This feature allows you to parse GFM tables from a Markdown string and convert them into an mdast syntax tree. The code sample demonstrates how to use the package in combination with 'mdast-util-from-markdown' to parse a simple table.

import { fromMarkdown } from 'mdast-util-from-markdown';
import { gfmTable } from 'mdast-util-gfm-table';

const markdown = '| Header 1 | Header 2 |\n| -------- | -------- |\n| Cell 1   | Cell 2   |';

const mdastTree = fromMarkdown(markdown, {
extensions: [gfmTable]
});

console.log(mdastTree);

Serializing GFM tables

This feature allows you to serialize an mdast syntax tree containing a GFM table back into a Markdown string. The code sample shows how to use the package with 'mdast-util-to-markdown' to serialize a simple mdast table structure.

import { toMarkdown } from 'mdast-util-to-markdown';
import { gfmTable } from 'mdast-util-gfm-table';

const mdastTree = {
type: 'table',
align: ['left', 'right'],
children: [
  {
type: 'tableRow',
children: [
    {type: 'tableCell', children: [{type: 'text', value: 'Header 1'}]},
    {type: 'tableCell', children: [{type: 'text', value: 'Header 2'}]}
  ]
},
  {
type: 'tableRow',
children: [
    {type: 'tableCell', children: [{type: 'text', value: 'Cell 1'}]},
    {type: 'tableCell', children: [{type: 'text', value: 'Cell 2'}]}
  ]
}
]
};

const markdown = toMarkdown(mdastTree, {
extensions: [gfmTable]
});

console.log(markdown);

Other packages similar to mdast-util-gfm-table

remark-gfm

remark-gfm is a plugin for remark, a Markdown processor powered by plugins part of the unified collective. It adds support for GFM features, including tables. It is similar to mdast-util-gfm-table but is designed to work within the remark ecosystem.

markdown-it

markdown-it is a Markdown parser with GFM table support built-in. It is a full parser, not just a utility for tables, and it is designed to be fast and highly extensible with plugins.

turndown-plugin-gfm

turndown-plugin-gfm is a plugin for Turndown, an HTML to Markdown converter. It adds GFM features, including tables, to the conversion process. It is similar in that it deals with tables in Markdown, but it is for converting from HTML rather than parsing and serializing Markdown directly.

README

mdast-util-gfm-table

mdast extensions to parse and serialize GFM tables.

Contents

• What is this?
• When to use this
• Install
• Use
• API
  • gfmTableFromMarkdown
  • gfmTableToMarkdown(options?)
  • Options
• Examples
  • Example: stringLength
• HTML
• Syntax
• Syntax tree
  • Nodes
  • Enumeration
  • Content model
• Types
• Compatibility
• Related
• Contribute
• License

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 14.14+ and 16.0+), 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@1'

In browsers with esm.sh:

<script type="module">
  import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'https://esm.sh/mdast-util-gfm-table@1?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 {fromMarkdown} from 'mdast-util-from-markdown'
import {toMarkdown} from 'mdast-util-to-markdown'
import {gfmTable} from 'micromark-extension-gfm-table'
import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'mdast-util-gfm-table'

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

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

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 {fromMarkdown} from 'mdast-util-from-markdown'
 import {toMarkdown} from 'mdast-util-to-markdown'
 import {gfmTable} from 'micromark-extension-gfm-table'
 import {gfmTableFromMarkdown, gfmTableToMarkdown} from 'mdast-util-gfm-table'
+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 {
  "left" | "right" | "center" | 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 all maintained versions of Node.js. As of now, that is Node.js 14.14+ and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

This plugin works with mdast-util-from-markdown version 1+ and mdast-util-to-markdown version 1+.

Related

• remarkjs/remark-gfm — remark plugin to support GFM
• syntax-tree/mdast-util-gfm — same but all of GFM (autolink literals, footnotes, strikethrough, tables, tasklists)
• micromark/micromark-extension-gfm-table — micromark extension to parse GFM tables

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