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Virtual file format for text processing


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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.



vfile is part of the unified collective.

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 in that vfile has a smaller API, a smaller size, and focuses on messages.


This package is ESM only. In Node.js (version 12.20+, 14.14, 16.0+), install with npm:

npm install vfile

In Deno with

import {VFile} from ''

In browsers with

<script type="module"> import {VFile} from '[email protected]?bundle' </script>


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) // => '' file.basename = 'index.text' console.log(file.history) // => ['~/example.txt', '~/', '~/index.text'] file.message('Unexpected unknown word `braavo`, did you mean `bravo`?', { line: 1, column: 8 }) console.log(file.messages)


[ [~/index.text:1:8: Unexpected unknown word `braavo`, did you mean `bravo`?] { reason: 'Unexpected unknown word `braavo`, did you mean `bravo`?', line: 1, column: 8, source: null, ruleId: null, position: {start: [Object], end: [Object]}, file: '~/index.text', fatal: false } ]


This package exports the identifier VFile. There is no default export.


Create a new virtual file.

  • if options is string or Buffer, it’s treated as {value: options}
  • if options is a URL, it’s treated as {path: options}
  • if options is a VFile, shallow copies its data over to the new file

All fields in options are set on the newly created VFile.

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

It’s not possible to set either dirname or extname without setting either history, path, basename, or stem as well.

new VFile() new VFile('console.log("alpha");') new VFile(Buffer.from('exit 1')) new VFile({path: path.join('path', 'to', '')}) new VFile({stem: 'readme', extname: '.md', dirname: path.join('path', 'to')}) new VFile({other: 'properties', are: 'copied', ov: {e: 'r'}})


Raw value (Buffer, string, null).


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


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.


Get or set the parent path (string?, example: '~'). Cannot be set if there’s no path yet.


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).


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.


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.


List of filepaths the file moved between (Array<string>). The first is the original path and the last is the current path.


List of messages associated with the file (Array<VFileMessage>).

Place to store custom information (Record<string, unknown>, default: {}). It’s OK to store custom data directly on the file but moving it to data is recommended.


Serialize the file. When value is a Buffer, encoding is a character encoding to understand it as (string, default: 'utf8').


Serialized file (string).

VFile#message(reason[, position][, origin])

Constructs a new VFileMessage, where fatal is set to false, and associates it with the file by adding it to file.messages and setting message.file to the current filepath.

  • reason (string or Error) — human readable reason for the message, uses the stack and message of the error if given
  • place (Node, Position, or Point, optional) — place where the message occurred in the file
  • origin (string?, optional, example: 'my-npm-package:my-rule-name') — computer readable reason for the message

Message (VFileMessage).

VFile#info(reason[, position][, origin])

Like VFile#message(), but associates an informational message where fatal is set to null.


Message (VFileMessage).

VFile#fail(reason[, position][, origin])

Like VFile#message(), but associates a fatal message where fatal is set to true, and then immediately throws it.

👉 Note: a fatal error means that a file is no longer processable.


Message (VFileMessage).

Well-known fields

The following fields are considered “non-standard”, but they are allowed, and some utilities use them:

  • stored (boolean) — whether a file was saved to disk, used by reporters
  • result (unknown) — sometimes files have a non-string, compiled, representation, which can be stored in the result field. One example is when turning markdown into React nodes. unified uses this field to store non-string results
  • map (Map) — sometimes files have a source map associated with them, this should be a Map type, which is equivalent to the RawSourceMap type from the source-map module

There are also well-known fields on messages, see them in a similar section of vfile-message.

List of utilities

👉 Note: see unist for projects that work with nodes.


👉 Note: want to make your own reporter? Reporters must accept Array<VFile> as their first argument, and return string. Reporters may accept other values too, in which case it’s suggested to stick to vfile-reporters interface.


This package is fully typed with TypeScript. It exports the following additional types:

  • BufferEncoding — thing that can be given as x in file.toString(x)
  • Compatible — everything that can be passed as x in new VFile(x)
  • Data — thing at
  • DataMap — interface you can add things to, to type your extensions of
  • Map — source map interface as supported at
  • Options — the fields that can be passed as options to new VFile(x)
  • Reporter — a reporter
  • ReporterSettings — the fields that can be passed to a reporter
  • Value — valid value
  • VFile — class of file itself

DataMap can be augmented to include your extensions to it:

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


Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.


See in vfile/.github for ways to get started. See 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.


Support this effort and give back by sponsoring on OpenCollective!










Boost Note




The initial release of this project was authored by @wooorm.

Thanks to @contra, @phated, and others for their work on Vinyl, which was a huge inspiration.

Thanks to @brendo, @shinnn, @KyleAMathews, @sindresorhus, and @denysdovhan for contributing commits since!


MIT © Titus Wormer



What is vfile?

Virtual file format for text processing

Is vfile popular?

The npm package vfile receives a total of 6,326,944 weekly downloads. As such, vfile popularity was classified as popular.

Is vfile well maintained?

We found that vfile demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago.It has 1 open source maintainer collaborating on the project.

Last updated on 17 Nov 2022

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