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8.1.1 • Public • Published


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vfile utility to create a report.

Example screenshot of vfile-reporter


What is this?

This package create a textual report from files showing the warnings that occurred while processing. Many CLIs of tools that process files, whether linters (such as ESLint) or bundlers (such as esbuild), have similar functionality.

When should I use this?

You can use this package when you want to display a report about what occurred while processing to a human.

There are other reporters that display information differently listed in vfile.


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

npm install vfile-reporter

In Deno with esm.sh:

import {reporter} from 'https://esm.sh/vfile-reporter@8'

In browsers with esm.sh:

<script type="module">
  import {reporter} from 'https://esm.sh/vfile-reporter@8?bundle'


Say our module example.js looks as follows:

import {VFile} from 'vfile'
import {reporter} from 'vfile-reporter'

const one = new VFile({path: 'test/fixture/1.js'})
const two = new VFile({path: 'test/fixture/2.js'})

one.message('Warning!', {line: 2, column: 4})

console.error(reporter([one, two]))

…now running node example.js yields:

2:4 warning Warning!

test/fixture/2.js: no issues found

⚠ 1 warning


This package exports the identifier reporter. That value is also the default export.

reporter(files[, options])

Create a report from one or more files.

  • files (Array<VFile> or VFile) — files to report
  • options (Options, optional) — configuration

Report (string).


Configuration (TypeScript type).

  • color (boolean, default: true when in Node.js and color is supported, or false) — use ANSI colors in report
  • defaultName (string, default: '<stdin>') — Label to use for files without file path; if one file and no defaultName is given, no name will show up in the report
  • verbose (boolean, default: false) — show message notes, URLs, and ancestor stack trace if available
  • quiet (boolean, default: false) — do not show files without messages
  • silent (boolean, default: false) — show errors only; this hides info and warning messages, and sets quiet: true
  • traceLimit (number, default: 10) — max number of nodes to show in ancestors trace); ancestors can be shown when verbose: true


Here’s a small example that looks through a markdown AST for emphasis and strong nodes, and checks whether they use *. The message has detailed information which will be shown in verbose mode.


import {fromMarkdown} from 'mdast-util-from-markdown'
import {visitParents} from 'unist-util-visit-parents'
import {VFile} from 'vfile'
import {reporter} from 'vfile-reporter'

const file = new VFile({
  path: new URL('example.md', import.meta.url),
  value: '# *hi*, _world_!'
const value = String(file)
const tree = fromMarkdown(value)
visitParents(tree, (node, parents) => {
  if (node.type === 'emphasis' || node.type === 'strong') {
    const start = node.position?.start.offset

    if (start !== undefined && value.charAt(start) === '_') {
      const m = file.message('Expected `*` (asterisk), not `_` (underscore)', {
        ancestors: [...parents, node],
        place: node.position,
        ruleId: 'attention-marker',
        source: 'some-lint-example'
      m.note = `It is recommended to use asterisks for emphasis/strong attention when
writing markdown.

There are some small differences in whether sequences can open and/or close…`
      m.url = 'https://example.com/whatever'

console.error(reporter([file], {verbose: false}))

…running node example.js yields:

1:9-1:16 warning Expected `*` (asterisk), not `_` (underscore) attention-marker some-lint-example

⚠ 1 warning

To show the info, pass verbose: true to reporter, and run again: and see:

1:9-1:16 warning Expected `*` (asterisk), not `_` (underscore) attention-marker some-lint-example
    It is recommended to use asterisks for emphasis/strong attention when
    writing markdown.

    There are some small differences in whether sequences can open and/or close…
    at emphasis (1:9-1:16)
    at heading (1:1-1:17)
    at root (1:1-1:17)

⚠ 1 warning


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


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, vfile-reporter@^8, compatible with Node.js 16.


Use of vfile-reporter is safe.



See contributing.md in vfile/.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, organisation, or community you agree to abide by its terms.


MIT © Titus Wormer

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