From da77de41ef2f904a2e30ecf528e7e97205000447 Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Fri, 30 Jul 2021 12:49:13 +0200
Subject: [PATCH] Use ESM

---
 package.json                           |   4 +-
 packages/rehype-cli/cli.js             |  13 +-
 packages/rehype-cli/package.json       |  10 +-
 packages/rehype-parse/errors.js        | 278 +++++++++++++++++++++++++
 packages/rehype-parse/errors.json      | 253 ----------------------
 packages/rehype-parse/index.js         |  18 +-
 packages/rehype-parse/package.json     |   9 +-
 packages/rehype-stringify/index.js     |   8 +-
 packages/rehype-stringify/package.json |   9 +-
 packages/rehype/index.js               |  10 +-
 packages/rehype/package.json           |   9 +-
 script/parse-error.js                  |  21 +-
 script/regenerate-fixtures.js          |  10 +-
 test/api.js                            |  22 +-
 test/cli.js                            |   8 +-
 test/index.js                          |   6 +-
 test/parse-error.js                    |  16 +-
 17 files changed, 362 insertions(+), 342 deletions(-)
 create mode 100644 packages/rehype-parse/errors.js
 delete mode 100644 packages/rehype-parse/errors.json

diff --git a/package.json b/package.json
index 97c80d3f..c90ab967 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,7 @@
     "type": "opencollective",
     "url": "https://opencollective.com/unified"
   },
+  "type": "module",
   "devDependencies": {
     "bail": "^1.0.0",
     "c8": "^7.0.0",
@@ -42,8 +43,9 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "unicorn/no-array-callback-reference": "off",
       "unicorn/prefer-number-properties": "off",
       "unicorn/prefer-optional-catch-binding": "off",
diff --git a/packages/rehype-cli/cli.js b/packages/rehype-cli/cli.js
index 96153fd0..396619bc 100755
--- a/packages/rehype-cli/cli.js
+++ b/packages/rehype-cli/cli.js
@@ -1,13 +1,14 @@
 #!/usr/bin/env node
-'use strict'
+import start from 'unified-args'
+import {rehype} from 'rehype'
+import {createRequire} from 'module'
+const require = createRequire(import.meta.url)
 
-var start = require('unified-args')
-var processor = require('rehype')
-var proc = require('rehype/package.json')
-var cli = require('./package.json')
+const proc = require('rehype/package.json')
+const cli = require('./package.json')
 
 start({
-  processor: processor,
+  processor: rehype,
   name: proc.name,
   description: cli.description,
   version: [
diff --git a/packages/rehype-cli/package.json b/packages/rehype-cli/package.json
index 8bf60b91..f7a31608 100644
--- a/packages/rehype-cli/package.json
+++ b/packages/rehype-cli/package.json
@@ -10,10 +10,6 @@
     "cli",
     "bin"
   ],
-  "dependencies": {
-    "rehype": "^11.0.0",
-    "unified-args": "^8.0.0"
-  },
   "repository": "https://github.com/rehypejs/rehype/tree/main/packages/rehype-cli",
   "bugs": "https://github.com/rehypejs/rehype/issues",
   "funding": {
@@ -24,12 +20,18 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "type": "module",
+  "main": "cli.js",
   "bin": {
     "rehype": "cli.js"
   },
   "files": [
     "cli.js"
   ],
+  "dependencies": {
+    "rehype": "^11.0.0",
+    "unified-args": "^8.0.0"
+  },
   "scripts": {},
   "xo": false
 }
diff --git a/packages/rehype-parse/errors.js b/packages/rehype-parse/errors.js
new file mode 100644
index 00000000..5c777395
--- /dev/null
+++ b/packages/rehype-parse/errors.js
@@ -0,0 +1,278 @@
+export const errors = {
+  abandonedHeadElementChild: {
+    reason: 'Unexpected metadata element after head',
+    description:
+      'Unexpected element after head. Expected the element before `</head>`',
+    url: false
+  },
+  abruptClosingOfEmptyComment: {
+    reason: 'Unexpected abruptly closed empty comment',
+    description: 'Unexpected `>` or `->`. Expected `-->` to close comments'
+  },
+  abruptDoctypePublicIdentifier: {
+    reason: 'Unexpected abruptly closed public identifier',
+    description:
+      'Unexpected `>`. Expected a closing `"` or `\'` after the public identifier'
+  },
+  abruptDoctypeSystemIdentifier: {
+    reason: 'Unexpected abruptly closed system identifier',
+    description:
+      'Unexpected `>`. Expected a closing `"` or `\'` after the identifier identifier'
+  },
+  absenceOfDigitsInNumericCharacterReference: {
+    reason: 'Unexpected non-digit at start of numeric character reference',
+    description:
+      'Unexpected `%c`. Expected `[0-9]` for decimal references or `[0-9a-fA-F]` for hexadecimal references'
+  },
+  cdataInHtmlContent: {
+    reason: 'Unexpected CDATA section in HTML',
+    description:
+      'Unexpected `<![CDATA[` in HTML. Remove it, use a comment, or encode special characters instead'
+  },
+  characterReferenceOutsideUnicodeRange: {
+    reason: 'Unexpected too big numeric character reference',
+    description:
+      'Unexpectedly high character reference. Expected character references to be at most hexadecimal 10ffff (or decimal 1114111)'
+  },
+  closingOfElementWithOpenChildElements: {
+    reason: 'Unexpected closing tag with open child elements',
+    description:
+      'Unexpectedly closing tag. Expected other tags to be closed first',
+    url: false
+  },
+  controlCharacterInInputStream: {
+    reason: 'Unexpected control character',
+    description:
+      'Unexpected control character `%x`. Expected a non-control code point, 0x00, or ASCII whitespace'
+  },
+  controlCharacterReference: {
+    reason: 'Unexpected control character reference',
+    description:
+      'Unexpectedly control character in reference. Expected a non-control code point, 0x00, or ASCII whitespace'
+  },
+  disallowedContentInNoscriptInHead: {
+    reason: 'Disallowed content inside `<noscript>` in `<head>`',
+    description:
+      'Unexpected text character `%c`. Only use text in `<noscript>`s in `<body>`',
+    url: false
+  },
+  duplicateAttribute: {
+    reason: 'Unexpected duplicate attribute',
+    description:
+      'Unexpectedly double attribute. Expected attributes to occur only once'
+  },
+  endTagWithAttributes: {
+    reason: 'Unexpected attribute on closing tag',
+    description: 'Unexpected attribute. Expected `>` instead'
+  },
+  endTagWithTrailingSolidus: {
+    reason: 'Unexpected slash at end of closing tag',
+    description: 'Unexpected `%c-1`. Expected `>` instead'
+  },
+  endTagWithoutMatchingOpenElement: {
+    reason: 'Unexpected unopened end tag',
+    description: 'Unexpected end tag. Expected no end tag or another end tag',
+    url: false
+  },
+  eofBeforeTagName: {
+    reason: 'Unexpected end of file',
+    description: 'Unexpected end of file. Expected tag name instead'
+  },
+  eofInCdata: {
+    reason: 'Unexpected end of file in CDATA',
+    description: 'Unexpected end of file. Expected `]]>` to close the CDATA'
+  },
+  eofInComment: {
+    reason: 'Unexpected end of file in comment',
+    description: 'Unexpected end of file. Expected `-->` to close the comment'
+  },
+  eofInDoctype: {
+    reason: 'Unexpected end of file in doctype',
+    description:
+      'Unexpected end of file. Expected a valid doctype (such as `<!doctype html>`)'
+  },
+  eofInElementThatCanContainOnlyText: {
+    reason: 'Unexpected end of file in element that can only contain text',
+    description: 'Unexpected end of file. Expected text or a closing tag',
+    url: false
+  },
+  eofInScriptHtmlCommentLikeText: {
+    reason: 'Unexpected end of file in comment inside script',
+    description: 'Unexpected end of file. Expected `-->` to close the comment'
+  },
+  eofInTag: {
+    reason: 'Unexpected end of file in tag',
+    description: 'Unexpected end of file. Expected `>` to close the tag'
+  },
+  incorrectlyClosedComment: {
+    reason: 'Incorrectly closed comment',
+    description: 'Unexpected `%c-1`. Expected `-->` to close the comment'
+  },
+  incorrectlyOpenedComment: {
+    reason: 'Incorrectly opened comment',
+    description: 'Unexpected `%c`. Expected `<!--` to open the comment'
+  },
+  invalidCharacterSequenceAfterDoctypeName: {
+    reason: 'Invalid sequence after doctype name',
+    description: 'Unexpected sequence at `%c`. Expected `public` or `system`'
+  },
+  invalidFirstCharacterOfTagName: {
+    reason: 'Invalid first character in tag name',
+    description: 'Unexpected `%c`. Expected an ASCII letter instead'
+  },
+  misplacedDoctype: {
+    reason: 'Misplaced doctype',
+    description: 'Unexpected doctype. Expected doctype before head',
+    url: false
+  },
+  misplacedStartTagForHeadElement: {
+    reason: 'Misplaced `<head>` start tag',
+    description:
+      'Unexpected start tag `<head>`. Expected `<head>` directly after doctype',
+    url: false
+  },
+  missingAttributeValue: {
+    reason: 'Missing attribute value',
+    description:
+      'Unexpected `%c-1`. Expected an attribute value or no `%c-1` instead'
+  },
+  missingDoctype: {
+    reason: 'Missing doctype before other content',
+    description: 'Expected a `<!doctype html>` before anything else',
+    url: false
+  },
+  missingDoctypeName: {
+    reason: 'Missing doctype name',
+    description: 'Unexpected doctype end at `%c`. Expected `html` instead'
+  },
+  missingDoctypePublicIdentifier: {
+    reason: 'Missing public identifier in doctype',
+    description: 'Unexpected `%c`. Expected identifier for `public` instead'
+  },
+  missingDoctypeSystemIdentifier: {
+    reason: 'Missing system identifier in doctype',
+    description:
+      'Unexpected `%c`. Expected identifier for `system` instead (suggested: `"about:legacy-compat"`)'
+  },
+  missingEndTagName: {
+    reason: 'Missing name in end tag',
+    description: 'Unexpected `%c`. Expected an ASCII letter instead'
+  },
+  missingQuoteBeforeDoctypePublicIdentifier: {
+    reason: 'Missing quote before public identifier in doctype',
+    description: 'Unexpected `%c`. Expected `"` or `\'` instead'
+  },
+  missingQuoteBeforeDoctypeSystemIdentifier: {
+    reason: 'Missing quote before system identifier in doctype',
+    description: 'Unexpected `%c`. Expected `"` or `\'` instead'
+  },
+  missingSemicolonAfterCharacterReference: {
+    reason: 'Missing semicolon after character reference',
+    description: 'Unexpected `%c`. Expected `;` instead'
+  },
+  missingWhitespaceAfterDoctypePublicKeyword: {
+    reason: 'Missing whitespace after public identifier in doctype',
+    description: 'Unexpected `%c`. Expected ASCII whitespace instead'
+  },
+  missingWhitespaceAfterDoctypeSystemKeyword: {
+    reason: 'Missing whitespace after system identifier in doctype',
+    description: 'Unexpected `%c`. Expected ASCII whitespace instead'
+  },
+  missingWhitespaceBeforeDoctypeName: {
+    reason: 'Missing whitespace before doctype name',
+    description: 'Unexpected `%c`. Expected ASCII whitespace instead'
+  },
+  missingWhitespaceBetweenAttributes: {
+    reason: 'Missing whitespace between attributes',
+    description: 'Unexpected `%c`. Expected ASCII whitespace instead'
+  },
+  missingWhitespaceBetweenDoctypePublicAndSystemIdentifiers: {
+    reason:
+      'Missing whitespace between public and system identifiers in doctype',
+    description: 'Unexpected `%c`. Expected ASCII whitespace instead'
+  },
+  nestedComment: {
+    reason: 'Unexpected nested comment',
+    description: 'Unexpected `<!--`. Expected `-->`'
+  },
+  nestedNoscriptInHead: {
+    reason: 'Unexpected nested `<noscript>` in `<head>`',
+    description:
+      'Unexpected `<noscript>`. Expected a closing tag or a meta element',
+    url: false
+  },
+  nonConformingDoctype: {
+    reason: 'Unexpected non-conforming doctype declaration',
+    description:
+      'Expected `<!doctype html>` or `<!doctype html system "about:legacy-compat">`',
+    url: false
+  },
+  nonVoidHtmlElementStartTagWithTrailingSolidus: {
+    reason: 'Unexpected trailing slash on start tag of non-void element',
+    description: 'Unexpected `/`. Expected `>` instead'
+  },
+  noncharacterCharacterReference: {
+    reason:
+      'Unexpected noncharacter code point referenced by character reference',
+    description: 'Unexpected code point. Do not use noncharacters in HTML'
+  },
+  noncharacterInInputStream: {
+    reason: 'Unexpected noncharacter character',
+    description: 'Unexpected code point `%x`. Do not use noncharacters in HTML'
+  },
+  nullCharacterReference: {
+    reason: 'Unexpected NULL character referenced by character reference',
+    description: 'Unexpected code point. Do not use NULL characters in HTML'
+  },
+  openElementsLeftAfterEof: {
+    reason: 'Unexpected end of file',
+    description: 'Unexpected end of file. Expected closing tag instead',
+    url: false
+  },
+  surrogateCharacterReference: {
+    reason: 'Unexpected surrogate character referenced by character reference',
+    description:
+      'Unexpected code point. Do not use lone surrogate characters in HTML'
+  },
+  surrogateInInputStream: {
+    reason: 'Unexpected surrogate character',
+    description:
+      'Unexpected code point `%x`. Do not use lone surrogate characters in HTML'
+  },
+  unexpectedCharacterAfterDoctypeSystemIdentifier: {
+    reason: 'Invalid character after system identifier in doctype',
+    description: 'Unexpected character at `%c`. Expected `>`'
+  },
+  unexpectedCharacterInAttributeName: {
+    reason: 'Unexpected character in attribute name',
+    description:
+      'Unexpected `%c`. Expected whitespace, `/`, `>`, `=`, or probably an ASCII letter'
+  },
+  unexpectedCharacterInUnquotedAttributeValue: {
+    reason: 'Unexpected character in unquoted attribute value',
+    description: 'Unexpected `%c`. Quote the attribute value to include it'
+  },
+  unexpectedEqualsSignBeforeAttributeName: {
+    reason: 'Unexpected equals sign before attribute name',
+    description: 'Unexpected `%c`. Add an attribute name before it'
+  },
+  unexpectedNullCharacter: {
+    reason: 'Unexpected NULL character',
+    description:
+      'Unexpected code point `%x`. Do not use NULL characters in HTML'
+  },
+  unexpectedQuestionMarkInsteadOfTagName: {
+    reason: 'Unexpected question mark instead of tag name',
+    description: 'Unexpected `%c`. Expected an ASCII letter instead'
+  },
+  unexpectedSolidusInTag: {
+    reason: 'Unexpected slash in tag',
+    description:
+      'Unexpected `%c-1`. Expected it followed by `>` or in a quoted attribute value'
+  },
+  unknownNamedCharacterReference: {
+    reason: 'Unexpected unknown named character reference',
+    description:
+      'Unexpected character reference. Expected known named character references'
+  }
+}
diff --git a/packages/rehype-parse/errors.json b/packages/rehype-parse/errors.json
deleted file mode 100644
index 2324cc76..00000000
--- a/packages/rehype-parse/errors.json
+++ /dev/null
@@ -1,253 +0,0 @@
-{
-  "abandonedHeadElementChild": {
-    "reason": "Unexpected metadata element after head",
-    "description": "Unexpected element after head. Expected the element before `</head>`",
-    "url": false
-  },
-  "abruptClosingOfEmptyComment": {
-    "reason": "Unexpected abruptly closed empty comment",
-    "description": "Unexpected `>` or `->`. Expected `-->` to close comments"
-  },
-  "abruptDoctypePublicIdentifier": {
-    "reason": "Unexpected abruptly closed public identifier",
-    "description": "Unexpected `>`. Expected a closing `\"` or `'` after the public identifier"
-  },
-  "abruptDoctypeSystemIdentifier": {
-    "reason": "Unexpected abruptly closed system identifier",
-    "description": "Unexpected `>`. Expected a closing `\"` or `'` after the identifier identifier"
-  },
-  "absenceOfDigitsInNumericCharacterReference": {
-    "reason": "Unexpected non-digit at start of numeric character reference",
-    "description": "Unexpected `%c`. Expected `[0-9]` for decimal references or `[0-9a-fA-F]` for hexadecimal references"
-  },
-  "cdataInHtmlContent": {
-    "reason": "Unexpected CDATA section in HTML",
-    "description": "Unexpected `<![CDATA[` in HTML. Remove it, use a comment, or encode special characters instead"
-  },
-  "characterReferenceOutsideUnicodeRange": {
-    "reason": "Unexpected too big numeric character reference",
-    "description": "Unexpectedly high character reference. Expected character references to be at most hexadecimal 10ffff (or decimal 1114111)"
-  },
-  "closingOfElementWithOpenChildElements": {
-    "reason": "Unexpected closing tag with open child elements",
-    "description": "Unexpectedly closing tag. Expected other tags to be closed first",
-    "url": false
-  },
-  "controlCharacterInInputStream": {
-    "reason": "Unexpected control character",
-    "description": "Unexpected control character `%x`. Expected a non-control code point, 0x00, or ASCII whitespace"
-  },
-  "controlCharacterReference": {
-    "reason": "Unexpected control character reference",
-    "description": "Unexpectedly control character in reference. Expected a non-control code point, 0x00, or ASCII whitespace"
-  },
-  "disallowedContentInNoscriptInHead": {
-    "reason": "Disallowed content inside `<noscript>` in `<head>`",
-    "description": "Unexpected text character `%c`. Only use text in `<noscript>`s in `<body>`",
-    "url": false
-  },
-  "duplicateAttribute": {
-    "reason": "Unexpected duplicate attribute",
-    "description": "Unexpectedly double attribute. Expected attributes to occur only once"
-  },
-  "endTagWithAttributes": {
-    "reason": "Unexpected attribute on closing tag",
-    "description": "Unexpected attribute. Expected `>` instead"
-  },
-  "endTagWithTrailingSolidus": {
-    "reason": "Unexpected slash at end of closing tag",
-    "description": "Unexpected `%c-1`. Expected `>` instead"
-  },
-  "endTagWithoutMatchingOpenElement": {
-    "reason": "Unexpected unopened end tag",
-    "description": "Unexpected end tag. Expected no end tag or another end tag",
-    "url": false
-  },
-  "eofBeforeTagName": {
-    "reason": "Unexpected end of file",
-    "description": "Unexpected end of file. Expected tag name instead"
-  },
-  "eofInCdata": {
-    "reason": "Unexpected end of file in CDATA",
-    "description": "Unexpected end of file. Expected `]]>` to close the CDATA"
-  },
-  "eofInComment": {
-    "reason": "Unexpected end of file in comment",
-    "description": "Unexpected end of file. Expected `-->` to close the comment"
-  },
-  "eofInDoctype": {
-    "reason": "Unexpected end of file in doctype",
-    "description": "Unexpected end of file. Expected a valid doctype (such as `<!doctype html>`)"
-  },
-  "eofInElementThatCanContainOnlyText": {
-    "reason": "Unexpected end of file in element that can only contain text",
-    "description": "Unexpected end of file. Expected text or a closing tag",
-    "url": false
-  },
-  "eofInScriptHtmlCommentLikeText": {
-    "reason": "Unexpected end of file in comment inside script",
-    "description": "Unexpected end of file. Expected `-->` to close the comment"
-  },
-  "eofInTag": {
-    "reason": "Unexpected end of file in tag",
-    "description": "Unexpected end of file. Expected `>` to close the tag"
-  },
-  "incorrectlyClosedComment": {
-    "reason": "Incorrectly closed comment",
-    "description": "Unexpected `%c-1`. Expected `-->` to close the comment"
-  },
-  "incorrectlyOpenedComment": {
-    "reason": "Incorrectly opened comment",
-    "description": "Unexpected `%c`. Expected `<!--` to open the comment"
-  },
-  "invalidCharacterSequenceAfterDoctypeName": {
-    "reason": "Invalid sequence after doctype name",
-    "description": "Unexpected sequence at `%c`. Expected `public` or `system`"
-  },
-  "invalidFirstCharacterOfTagName": {
-    "reason": "Invalid first character in tag name",
-    "description": "Unexpected `%c`. Expected an ASCII letter instead"
-  },
-  "misplacedDoctype": {
-    "reason": "Misplaced doctype",
-    "description": "Unexpected doctype. Expected doctype before head",
-    "url": false
-  },
-  "misplacedStartTagForHeadElement": {
-    "reason": "Misplaced `<head>` start tag",
-    "description": "Unexpected start tag `<head>`. Expected `<head>` directly after doctype",
-    "url": false
-  },
-  "missingAttributeValue": {
-    "reason": "Missing attribute value",
-    "description": "Unexpected `%c-1`. Expected an attribute value or no `%c-1` instead"
-  },
-  "missingDoctype": {
-    "reason": "Missing doctype before other content",
-    "description": "Expected a `<!doctype html>` before anything else",
-    "url": false
-  },
-  "missingDoctypeName": {
-    "reason": "Missing doctype name",
-    "description": "Unexpected doctype end at `%c`. Expected `html` instead"
-  },
-  "missingDoctypePublicIdentifier": {
-    "reason": "Missing public identifier in doctype",
-    "description": "Unexpected `%c`. Expected identifier for `public` instead"
-  },
-  "missingDoctypeSystemIdentifier": {
-    "reason": "Missing system identifier in doctype",
-    "description": "Unexpected `%c`. Expected identifier for `system` instead (suggested: `\"about:legacy-compat\"`)"
-  },
-  "missingEndTagName": {
-    "reason": "Missing name in end tag",
-    "description": "Unexpected `%c`. Expected an ASCII letter instead"
-  },
-  "missingQuoteBeforeDoctypePublicIdentifier": {
-    "reason": "Missing quote before public identifier in doctype",
-    "description": "Unexpected `%c`. Expected `\"` or `'` instead"
-  },
-  "missingQuoteBeforeDoctypeSystemIdentifier": {
-    "reason": "Missing quote before system identifier in doctype",
-    "description": "Unexpected `%c`. Expected `\"` or `'` instead"
-  },
-  "missingSemicolonAfterCharacterReference": {
-    "reason": "Missing semicolon after character reference",
-    "description": "Unexpected `%c`. Expected `;` instead"
-  },
-  "missingWhitespaceAfterDoctypePublicKeyword": {
-    "reason": "Missing whitespace after public identifier in doctype",
-    "description": "Unexpected `%c`. Expected ASCII whitespace instead"
-  },
-  "missingWhitespaceAfterDoctypeSystemKeyword": {
-    "reason": "Missing whitespace after system identifier in doctype",
-    "description": "Unexpected `%c`. Expected ASCII whitespace instead"
-  },
-  "missingWhitespaceBeforeDoctypeName": {
-    "reason": "Missing whitespace before doctype name",
-    "description": "Unexpected `%c`. Expected ASCII whitespace instead"
-  },
-  "missingWhitespaceBetweenAttributes": {
-    "reason": "Missing whitespace between attributes",
-    "description": "Unexpected `%c`. Expected ASCII whitespace instead"
-  },
-  "missingWhitespaceBetweenDoctypePublicAndSystemIdentifiers": {
-    "reason": "Missing whitespace between public and system identifiers in doctype",
-    "description": "Unexpected `%c`. Expected ASCII whitespace instead"
-  },
-  "nestedComment": {
-    "reason": "Unexpected nested comment",
-    "description": "Unexpected `<!--`. Expected `-->`"
-  },
-  "nestedNoscriptInHead": {
-    "reason": "Unexpected nested `<noscript>` in `<head>`",
-    "description": "Unexpected `<noscript>`. Expected a closing tag or a meta element",
-    "url": false
-  },
-  "nonConformingDoctype": {
-    "reason": "Unexpected non-conforming doctype declaration",
-    "description": "Expected `<!doctype html>` or `<!doctype html system \"about:legacy-compat\">`",
-    "url": false
-  },
-  "nonVoidHtmlElementStartTagWithTrailingSolidus": {
-    "reason": "Unexpected trailing slash on start tag of non-void element",
-    "description": "Unexpected `/`. Expected `>` instead"
-  },
-  "noncharacterCharacterReference": {
-    "reason": "Unexpected noncharacter code point referenced by character reference",
-    "description": "Unexpected code point. Do not use noncharacters in HTML"
-  },
-  "noncharacterInInputStream": {
-    "reason": "Unexpected noncharacter character",
-    "description": "Unexpected code point `%x`. Do not use noncharacters in HTML"
-  },
-  "nullCharacterReference": {
-    "reason": "Unexpected NULL character referenced by character reference",
-    "description": "Unexpected code point. Do not use NULL characters in HTML"
-  },
-  "openElementsLeftAfterEof": {
-    "reason": "Unexpected end of file",
-    "description": "Unexpected end of file. Expected closing tag instead",
-    "url": false
-  },
-  "surrogateCharacterReference": {
-    "reason": "Unexpected surrogate character referenced by character reference",
-    "description": "Unexpected code point. Do not use lone surrogate characters in HTML"
-  },
-  "surrogateInInputStream": {
-    "reason": "Unexpected surrogate character",
-    "description": "Unexpected code point `%x`. Do not use lone surrogate characters in HTML"
-  },
-  "unexpectedCharacterAfterDoctypeSystemIdentifier": {
-    "reason": "Invalid character after system identifier in doctype",
-    "description": "Unexpected character at `%c`. Expected `>`"
-  },
-  "unexpectedCharacterInAttributeName": {
-    "reason": "Unexpected character in attribute name",
-    "description": "Unexpected `%c`. Expected whitespace, `/`, `>`, `=`, or probably an ASCII letter"
-  },
-  "unexpectedCharacterInUnquotedAttributeValue": {
-    "reason": "Unexpected character in unquoted attribute value",
-    "description": "Unexpected `%c`. Quote the attribute value to include it"
-  },
-  "unexpectedEqualsSignBeforeAttributeName": {
-    "reason": "Unexpected equals sign before attribute name",
-    "description": "Unexpected `%c`. Add an attribute name before it"
-  },
-  "unexpectedNullCharacter": {
-    "reason": "Unexpected NULL character",
-    "description": "Unexpected code point `%x`. Do not use NULL characters in HTML"
-  },
-  "unexpectedQuestionMarkInsteadOfTagName": {
-    "reason": "Unexpected question mark instead of tag name",
-    "description": "Unexpected `%c`. Expected an ASCII letter instead"
-  },
-  "unexpectedSolidusInTag": {
-    "reason": "Unexpected slash in tag",
-    "description": "Unexpected `%c-1`. Expected it followed by `>` or in a quoted attribute value"
-  },
-  "unknownNamedCharacterReference": {
-    "reason": "Unexpected unknown named character reference",
-    "description": "Unexpected character reference. Expected known named character references"
-  }
-}
diff --git a/packages/rehype-parse/index.js b/packages/rehype-parse/index.js
index 771b646f..446b76d2 100644
--- a/packages/rehype-parse/index.js
+++ b/packages/rehype-parse/index.js
@@ -1,16 +1,12 @@
-'use strict'
-
-var fromParse5 = require('hast-util-from-parse5')
-var Parser5 = require('parse5/lib/parser')
-var errors = require('./errors.json')
+import fromParse5 from 'hast-util-from-parse5'
+import Parser5 from 'parse5/lib/parser/index.js'
+import {errors} from './errors.js'
 
 var base = 'https://html.spec.whatwg.org/multipage/parsing.html#parse-error-'
 
 var fatalities = {2: true, 1: false, 0: null}
 
-module.exports = parse
-
-function parse(options) {
+export default function rehypeParse(options) {
   var settings = Object.assign({}, options, this.data('settings'))
   var position = settings.position
 
@@ -23,13 +19,13 @@ function parse(options) {
     var onParseError = settings.emitParseErrors ? onerror : null
     var parse5 = new Parser5({
       sourceCodeLocationInfo: position,
-      onParseError: onParseError,
+      onParseError,
       scriptingEnabled: false
     })
 
     return fromParse5(parse5[fn](doc), {
       space: settings.space,
-      file: file,
+      file,
       verbose: settings.verbose
     })
 
@@ -56,7 +52,7 @@ function parse(options) {
         /* c8 ignore next */
         info = errors[name] || {reason: '', description: ''}
 
-        message = file.message(format(info.reason), {start: start, end: end})
+        message = file.message(format(info.reason), {start, end})
         message.source = 'parse-error'
         message.ruleId = code
         message.fatal = fatalities[level]
diff --git a/packages/rehype-parse/package.json b/packages/rehype-parse/package.json
index b219fb5d..3dc46cd9 100644
--- a/packages/rehype-parse/package.json
+++ b/packages/rehype-parse/package.json
@@ -26,12 +26,15 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
+  "types": "types/index.d.ts",
   "files": [
-    "index.js",
     "types/index.d.ts",
-    "errors.json"
+    "errors.js",
+    "index.js"
   ],
-  "types": "types/index.d.ts",
   "dependencies": {
     "hast-util-from-parse5": "^6.0.0",
     "parse5": "^6.0.0"
diff --git a/packages/rehype-stringify/index.js b/packages/rehype-stringify/index.js
index 22335dab..dd344f33 100644
--- a/packages/rehype-stringify/index.js
+++ b/packages/rehype-stringify/index.js
@@ -1,10 +1,6 @@
-'use strict'
+import toHTML from 'hast-util-to-html'
 
-var toHTML = require('hast-util-to-html')
-
-module.exports = stringify
-
-function stringify(config) {
+export default function rehypeStringify(config) {
   var settings = Object.assign({}, config, this.data('settings'))
 
   this.Compiler = compiler
diff --git a/packages/rehype-stringify/package.json b/packages/rehype-stringify/package.json
index 47f5fa20..37a771a9 100644
--- a/packages/rehype-stringify/package.json
+++ b/packages/rehype-stringify/package.json
@@ -28,11 +28,14 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
+  "types": "types/index.d.ts",
   "files": [
-    "index.js",
-    "types/index.d.ts"
+    "types/index.d.ts",
+    "index.js"
   ],
-  "types": "types/index.d.ts",
   "dependencies": {
     "hast-util-to-html": "^7.1.1"
   },
diff --git a/packages/rehype/index.js b/packages/rehype/index.js
index f8c2b482..b5e443e4 100644
--- a/packages/rehype/index.js
+++ b/packages/rehype/index.js
@@ -1,7 +1,5 @@
-'use strict'
+import unified from 'unified'
+import rehypeParse from 'rehype-parse'
+import rehypeStringify from 'rehype-stringify'
 
-var unified = require('unified')
-var parse = require('rehype-parse')
-var stringify = require('rehype-stringify')
-
-module.exports = unified().use(parse).use(stringify).freeze()
+export const rehype = unified().use(rehypeParse).use(rehypeStringify).freeze()
diff --git a/packages/rehype/package.json b/packages/rehype/package.json
index f7ade2d4..b9af75ac 100644
--- a/packages/rehype/package.json
+++ b/packages/rehype/package.json
@@ -32,11 +32,14 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
+  "types": "types/index.d.ts",
   "files": [
-    "index.js",
-    "types/index.d.ts"
+    "types/index.d.ts",
+    "index.js"
   ],
-  "types": "types/index.d.ts",
   "scripts": {},
   "xo": false
 }
diff --git a/script/parse-error.js b/script/parse-error.js
index e05a774a..f41d7ddd 100644
--- a/script/parse-error.js
+++ b/script/parse-error.js
@@ -1,12 +1,13 @@
-'use strict'
+import fs from 'fs'
+import u from 'unist-builder'
+import unified from 'unified'
+import parse from 'remark-parse'
+import zone from 'mdast-zone'
+import {errors} from '../packages/rehype-parse/errors.js'
 
-var u = require('unist-builder')
-var unified = require('unified')
-var parse = require('remark-parse')
-var zone = require('mdast-zone')
-var errors = require('../packages/rehype-parse/errors.json')
+const pkg = JSON.parse(fs.readFileSync('package.json'))
 
-var repo = require('../package.json').repository
+var repo = pkg.repository
 
 var whatwg = 'https://html.spec.whatwg.org/multipage/parsing.html#parse-error-'
 var base = 'https://github.com/' + repo + '/blob/main'
@@ -15,9 +16,7 @@ var ignoreFixture = {
   surrogateInInputStream: true
 }
 
-module.exports = parseErrors
-
-function parseErrors() {
+export default function remarkParseErrors() {
   return transform
 }
 
@@ -25,7 +24,7 @@ function transform(tree) {
   zone(tree, 'parse-error', visit)
 }
 
-function visit(start, nodes, end) {
+function visit(start, _, end) {
   return [
     start,
     u('list', {ordered: false, spread: false}, Object.keys(errors).map(map)),
diff --git a/script/regenerate-fixtures.js b/script/regenerate-fixtures.js
index 12673c63..ece2ae9e 100644
--- a/script/regenerate-fixtures.js
+++ b/script/regenerate-fixtures.js
@@ -1,9 +1,7 @@
-'use strict'
-
-var fs = require('fs')
-var path = require('path')
-var bail = require('bail')
-var rehype = require('../packages/rehype/index.js')
+import fs from 'fs'
+import path from 'path'
+import bail from 'bail'
+import rehype from '../packages/rehype/index.js'
 
 var join = path.join
 
diff --git a/test/api.js b/test/api.js
index 2a7ea4a5..d1ec6ba3 100644
--- a/test/api.js
+++ b/test/api.js
@@ -1,15 +1,13 @@
-'use strict'
-
-var fs = require('fs')
-var path = require('path')
-var test = require('tape')
-var vfile = require('to-vfile')
-var clean = require('unist-util-remove-position')
-var hast = require('hast-util-assert')
-var unified = require('../packages/rehype/node_modules/unified/index.js')
-var parse = require('../packages/rehype-parse/index.js')
-var stringify = require('../packages/rehype-stringify/index.js')
-var rehype = require('../packages/rehype/index.js')
+import fs from 'fs'
+import path from 'path'
+import test from 'tape'
+import vfile from 'to-vfile'
+import clean from 'unist-util-remove-position'
+import hast from 'hast-util-assert'
+import unified from '../packages/rehype/node_modules/unified/index.js'
+import parse from '../packages/rehype-parse/index.js'
+import stringify from '../packages/rehype-stringify/index.js'
+import {rehype} from '../packages/rehype/index.js'
 
 var fragment = {fragment: true}
 
diff --git a/test/cli.js b/test/cli.js
index 9ae78464..3b20717d 100644
--- a/test/cli.js
+++ b/test/cli.js
@@ -1,8 +1,6 @@
-'use strict'
-
-var path = require('path')
-var exec = require('child_process').exec
-var test = require('tape')
+import path from 'path'
+import {exec} from 'child_process'
+import test from 'tape'
 
 var join = path.join
 
diff --git a/test/index.js b/test/index.js
index 3022b14f..3bc313da 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,7 +1,7 @@
 'use strict'
 
 /* eslint-disable import/no-unassigned-import */
-require('./api.js')
-require('./parse-error.js')
-require('./cli.js')
+import './api.js'
+import './parse-error.js'
+import './cli.js'
 /* eslint-enable import/no-unassigned-import */
diff --git a/test/parse-error.js b/test/parse-error.js
index ba9a012d..5efa63d9 100644
--- a/test/parse-error.js
+++ b/test/parse-error.js
@@ -1,12 +1,10 @@
-'use strict'
-
-var fs = require('fs')
-var path = require('path')
-var test = require('tape')
-var vfile = require('to-vfile')
-var rehype = require('../packages/rehype/index.js')
-var p5errors = require('../packages/rehype-parse/node_modules/parse5/lib/common/error-codes.js')
-var rerrors = require('../packages/rehype-parse/errors.json')
+import fs from 'fs'
+import path from 'path'
+import test from 'tape'
+import vfile from 'to-vfile'
+import {rehype} from '../packages/rehype/index.js'
+import p5errors from '../packages/rehype-parse/node_modules/parse5/lib/common/error-codes.js'
+import {errors as rerrors} from '../packages/rehype-parse/errors.js'
 
 // Related to https://github.com/inikulin/parse5/issues/255
 // and https://github.com/inikulin/parse5/pull/257.