Vfile

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vfile is a small and browser friendly virtual file format that tracks metadata about files (such as its path and value) and lint [messages][api-vfile-messages].

Contents

• unified
• What is this?
• When should I use this?
• Install
• Use
• API
  • VFile(options?)
  • file.cwd
  • file.data
  • file.history
  • file.messages
  • file.value
  • file.basename
  • file.dirname
  • file.extname
  • file.path
  • file.stem
  • VFile#fail(reason[, options])
  • VFile#info(reason[, options])
  • VFile#message(reason[, options])
  • VFile#toString(encoding?)
  • Compatible
  • Data
  • DataMap
  • Map
  • MessageOptions
  • Options
  • Reporter
  • ReporterSettings
  • Value
  • Well-known
• List of utilities
• Reporters
• Types
• Compatibility
• Contribute
• Sponsor
• Acknowledgments
• License

unified

vfile is part of the unified collective.

• for more about us, see [unifiedjs.com][site]
• for how the collective is governed, see [unifiedjs/collective][governance]

What is this?

This package provides a virtual file format. It exposes an API to access the file value, path, metadata about the file, and specifically supports attaching lint messages and errors to certain places in these files.

When should I use this?

The virtual file format is useful when dealing with the concept of files in places where you might not be able to access the file system. The message API is particularly useful when making things that check files (as in, linting).

vfile is made for [unified][], which amongst other things checks files. However, vfile can be used in other projects that deal with parsing, transforming, and serializing data, to build linters, compilers, static site generators, and other build tools.

This is different from the excellent [vinyl][vinyl] in that vfile has a smaller API, a smaller size, and focuses on messages.

Install

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

npm install vfile

In Deno with [esm.sh][esmsh]:

import {VFile} from 'https://esm.sh/vfile@6'

In browsers with [esm.sh][esmsh]:

<script type="module">
  import {VFile} from 'https://esm.sh/vfile@6?bundle'
</script>

Use

import {VFile} from 'vfile'

const file = new VFile({
  path: '~/example.txt',
  value: 'Alpha *braavo* charlie.'
})

console.log(file.path) // => '~/example.txt'
console.log(file.dirname) // => '~'

file.extname = '.md'

console.log(file.basename) // => 'example.md'

file.basename = 'index.text'

console.log(file.history) // => ['~/example.txt', '~/example.md', '~/index.text']

file.message('Unexpected unknown word `braavo`, did you mean `bravo`?', {
  place: {line: 1, column: 8},
  source: 'spell',
  ruleId: 'typo'
})

console.log(file.messages)

Yields:

[
  [~/index.text:1:8: Unexpected unknown word `braavo`, did you mean `bravo`?] {
    ancestors: undefined,
    cause: undefined,
    column: 8,
    fatal: false,
    line: 1,
    place: { line: 1, column: 8 },
    reason: 'Unexpected unknown word `braavo`, did you mean `bravo`?',
    ruleId: 'typo',
    source: 'spell',
    file: '~/index.text'
  }
]

API

This package exports the identifier [VFile][api-vfile]. There is no default export.

VFile(options?)

Create a new virtual file.

options is treated as:

• string or [Uint8Array][mdn-uint8-array] — {value: options}
• URL — {path: options}
• VFile — shallow copies its data over to the new file
• object — all fields are shallow copied over to the new file

Path related fields are set in the following order (least specific to most specific): history, path, basename, stem, extname, dirname.

You cannot set dirname or extname without setting either history, path, basename, or stem too.

Parameters

• options ([Compatible][api-compatible], optional) — file value

Returns

New instance (VFile).

Example

new VFile()
new VFile('console.log("alpha");')
new VFile(new Uint8Array([0x65, 0x78, 0x69, 0x74, 0x20, 0x31]))
new VFile({path: path.join('path', 'to', 'readme.md')})
new VFile({stem: 'readme', extname: '.md', dirname: path.join('path', 'to')})
new VFile({other: 'properties', are: 'copied', ov: {e: 'r'}})

file.cwd

Base of path (string, default: process.cwd() or '/' in browsers).

file.data

Place to store custom info (Record<string, unknown>, default: {}).

It’s OK to store custom data directly on the file but moving it to data is recommended.

file.history

List of file paths the file moved between (Array<string>).

The first is the original path and the last is the current path.

file.messages

List of messages associated with the file ([Array<VFileMessage>][api-vfile-message]).

file.value

Raw value ([Uint8Array][mdn-uint8-array], string, undefined).

file.basename

Get or set the basename (including extname) (string?, example: 'index.min.js').

Cannot contain path separators ('/' on unix, macOS, and browsers, '\' on windows). Cannot be nullified (use file.path = file.dirname instead).

file.dirname

Get or set the parent path (string?, example: '~').

Cannot be set if there’s no path yet.

file.extname

Get or set the extname (including dot) (string?, example: '.js').

Cannot contain path separators ('/' on unix, macOS, and browsers, '\' on windows). Cannot be set if there’s no path yet.

file.path

Get or set the full path (string?, example: '~/index.min.js').

Cannot be nullified. You can set a file URL (a URL object with a file: protocol) which will be turned into a path with [url.fileURLToPath][file-url-to-path].

file.stem

Get or set the stem (basename w/o extname) (string?, example: 'index.min').

Cannot contain path separators ('/' on unix, macOS, and browsers, '\' on windows). Cannot be nullified.

VFile#fail(reason[, options])

Create a fatal message for reason associated with the file.

The fatal field of the message is set to true (error; file not usable) and the file field is set to the current file path. The message is added to the messages field on file.

🪦 Note: also has obsolete signatures.

Parameters

• reason (string) — reason for message, should use markdown
• options ([MessageOptions][api-message-options], optional) — configuration

Returns

Nothing (never).

Throws

Message ([VFileMessage][vmessage]).

VFile#info(reason[, options])

Create an info message for reason associated with the file.

The fatal field of the message is set to undefined (info; change likely not needed) and the file field is set to the current file path. The message is added to the messages field on file.

🪦 Note: also has obsolete signatures.

Parameters

• reason (string) — reason for message, should use markdown
• options ([MessageOptions][api-message-options], optional) — configuration

Returns

Message ([VFileMessage][vmessage]).

VFile#message(reason[, options])

Create a message for reason associated with the file.

The fatal field of the message is set to false (warning; change may be needed) and the file field is set to the current file path. The message is added to the messages field on file.

🪦 Note: also has obsolete signatures.

Parameters

• reason (string) — reason for message, should use markdown
• options ([MessageOptions][api-message-options], optional) — configuration

Returns

Message ([VFileMessage][vmessage]).

VFile#toString(encoding?)

Serialize the file.

Note: which encodings are supported depends on the engine. For info on Node.js, see: https://nodejs.org/api/util.html#whatwg-supported-encodings.

Parameters

• encoding (string, default: 'utf8') — character encoding to understand value as when it’s a [Uint8Array][mdn-uint8-array]

Returns

Serialized file (string).

Compatible

Things that can be passed to the constructor (TypeScript type).

Type

type Compatible = Options | URL | VFile | Value

Data

Custom info (TypeScript type).

Known attributes can be added to [DataMap][api-data-map].

Type

type Data = Record<string, unknown> & Partial<DataMap>

DataMap

This map registers the type of the data key of a VFile (TypeScript type).

This type can be augmented to register custom data types.

Type

interface DataMap {}

Example

declare module 'vfile' {
  interface DataMap {
    // `file.data.name` is typed as `string`
    name: string
  }
}

Map

Raw source map (TypeScript type).

See [source-map][source-map].

Fields

• version (number) — which version of the source map spec this map is following
• sources (`Array<st