Use ESM

Author: wooorm

.gitignore

@@ -1,6 +1,5 @@
-.DS_Store
-*.log
-.nyc_output/
 coverage/
 node_modules/
+.DS_Store
+*.log
 yarn.lock

.prettierignore

@@ -1,3 +1,2 @@
 coverage/
-*.json
 *.md

from-markdown.js

@@ -1,2 +1,132 @@
-exports.fromMarkdown = require('./from-markdown.js')
-exports.toMarkdown = require('./to-markdown.js')
+import normalizeIdentifier from 'micromark/dist/util/normalize-identifier.js'
+import association from 'mdast-util-to-markdown/lib/util/association.js'
+import phrasing from 'mdast-util-to-markdown/lib/util/container-phrasing.js'
+import flow from 'mdast-util-to-markdown/lib/util/container-flow.js'
+import indentLines from 'mdast-util-to-markdown/lib/util/indent-lines.js'
+import safe from 'mdast-util-to-markdown/lib/util/safe.js'
+
+export const footnoteFromMarkdown = {
+  canContainEols: ['footnote'],
+  enter: {
+    footnoteDefinition: enterFootnoteDefinition,
+    footnoteDefinitionLabelString: enterFootnoteDefinitionLabelString,
+    footnoteCall: enterFootnoteCall,
+    footnoteCallString: enterFootnoteCallString,
+    inlineNote: enterNote
+  },
+  exit: {
+    footnoteDefinition: exitFootnoteDefinition,
+    footnoteDefinitionLabelString: exitFootnoteDefinitionLabelString,
+    footnoteCall: exitFootnoteCall,
+    footnoteCallString: exitFootnoteCallString,
+    inlineNote: exitNote
+  }
+}
+
+export const footnoteToMarkdown = {
+  // This is on by default already.
+  unsafe: [{character: '[', inConstruct: ['phrasing', 'label', 'reference']}],
+  handlers: {footnote, footnoteDefinition, footnoteReference}
+}
+
+footnoteReference.peek = footnoteReferencePeek
+footnote.peek = footnotePeek
+
+function enterFootnoteDefinition(token) {
+  this.enter(
+    {type: 'footnoteDefinition', identifier: '', label: '', children: []},
+    token
+  )
+}
+
+function enterFootnoteDefinitionLabelString() {
+  this.buffer()
+}
+
+function exitFootnoteDefinitionLabelString(token) {
+  var label = this.resume()
+  this.stack[this.stack.length - 1].label = label
+  this.stack[this.stack.length - 1].identifier = normalizeIdentifier(
+    this.sliceSerialize(token)
+  ).toLowerCase()
+}
+
+function exitFootnoteDefinition(token) {
+  this.exit(token)
+}
+
+function enterFootnoteCall(token) {
+  this.enter({type: 'footnoteReference', identifier: '', label: ''}, token)
+}
+
+function enterFootnoteCallString() {
+  this.buffer()
+}
+
+function exitFootnoteCallString(token) {
+  var label = this.resume()
+  this.stack[this.stack.length - 1].label = label
+  this.stack[this.stack.length - 1].identifier = normalizeIdentifier(
+    this.sliceSerialize(token)
+  ).toLowerCase()
+}
+
+function exitFootnoteCall(token) {
+  this.exit(token)
+}
+
+function enterNote(token) {
+  this.enter({type: 'footnote', children: []}, token)
+}
+
+function exitNote(token) {
+  this.exit(token)
+}
+
+function footnoteReference(node, _, context) {
+  var exit = context.enter('footnoteReference')
+  var subexit = context.enter('reference')
+  var reference = safe(context, association(node), {before: '^', after: ']'})
+  subexit()
+  exit()
+  return '[^' + reference + ']'
+}
+
+function footnoteReferencePeek() {
+  return '['
+}
+
+function footnote(node, _, context) {
+  var exit = context.enter('footnote')
+  var subexit = context.enter('label')
+  var value = '^[' + phrasing(node, context, {before: '[', after: ']'}) + ']'
+  subexit()
+  exit()
+  return value
+}
+
+function footnotePeek() {
+  return '^'
+}
+
+function footnoteDefinition(node, _, context) {
+  var exit = context.enter('footnoteDefinition')
+  var subexit = context.enter('label')
+  var label =
+    '[^' + safe(context, association(node), {before: '^', after: ']'}) + ']:'
+  var value
+  subexit()
+
+  value = indentLines(flow(node, context), map)
+  exit()
+
+  return value
+
+  function map(line, index, blank) {
+    if (index) {
+      return (blank ? '' : '    ') + line
+    }
+
+    return (blank ? label : label + ' ') + line
+  }
+}

index.js

@@ -25,37 +25,32 @@
   "contributors": [
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
   "files": [
-    "from-markdown.js",
-    "index.js",
-    "to-markdown.js"
+    "index.js"
   ],
   "dependencies": {
     "mdast-util-to-markdown": "^0.6.0",
     "micromark": "~2.11.0"
   },
   "devDependencies": {
+    "c8": "^7.0.0",
     "mdast-util-from-markdown": "^0.8.0",
     "micromark-extension-footnote": "~0.3.0",
-    "nyc": "^15.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
     "tape": "^5.0.0",
-    "xo": "^0.38.0"
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
-    "test-api": "node test",
-    "test-coverage": "nyc --reporter lcov tape test.js",
+    "test-api": "node --conditions development test.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node --conditions development test.js",
     "test": "npm run format && npm run test-coverage"
   },
-  "nyc": {
-    "check-coverage": true,
-    "lines": 100,
-    "functions": 100,
-    "branches": 100
-  },
   "prettier": {
     "tabWidth": 2,
     "useTabs": false,
@@ -66,7 +61,10 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false
+    "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off"
+    }
   },
   "remarkConfig": {
     "plugins": [

package.json

@@ -18,6 +18,9 @@ You probably shouldn’t use this package directly, but instead use
 
 ## Install
 
+This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c):
+Node 12+ is needed to use it and it must be `import`ed instead of `require`d.
+
 [npm][]:
 
 ```sh
@@ -173,13 +176,13 @@ note.]
 
 ## API
 
-### `footnote.fromMarkdown`
+This package exports the following identifier: `footnoteFromMarkdown`,
+`footnoteToMarkdown`.
+There is no default export.
 
-### `footnote.toMarkdown`
+### `footnoteFromMarkdown`
 
-> Note: the separate extensions are also available at
-> `mdast-util-footnote/from-markdown` and
-> `mdast-util-footnote/to-markdown`.
+### `footnoteToMarkdown`
 
 Support footnotes.
 These exports are extensions, respectively for