Use ESM and update vfile

*   **Breaking**: this updates `vfile`, which importantly renames
    ~~`vfile.contents`~~ to `vfile.value`
*   Inconsequential: this updates `trough`, which removes support
    for Promise-like objects, in favor of only support actual
    promises.
    To update, instead of returning an object with a `then` function,
    return and *actual* promise

.gitignore

@@ -1,8 +1,5 @@
 .DS_Store
 *.log
-.nyc_output/
 coverage/
 node_modules/
-unified.js
-unified.min.js
 yarn.lock

.prettierignore

@@ -1,5 +1,2 @@
 coverage/
-unified.js
-unified.min.js
-*.json
 *.md

index.js

@@ -1,14 +1,12 @@
-'use strict'
-
-var bail = require('bail')
-var buffer = require('is-buffer')
-var extend = require('extend')
-var plain = require('is-plain-obj')
-var trough = require('trough')
-var vfile = require('vfile')
+import {bail} from 'bail'
+import isBuffer from 'is-buffer'
+import extend from 'extend'
+import isPlainObj from 'is-plain-obj'
+import {trough} from 'trough'
+import {VFile} from 'vfile'
 
 // Expose a frozen processor.
-module.exports = unified().freeze()
+export const unified = base().freeze()
 
 var slice = [].slice
 var own = {}.hasOwnProperty
@@ -42,15 +40,15 @@ function pipelineStringify(p, ctx) {
 
   if (result === undefined || result === null) {
     // Empty.
-  } else if (typeof result === 'string' || buffer(result)) {
-    ctx.file.contents = result
+  } else if (typeof result === 'string' || isBuffer(result)) {
+    ctx.file.value = result
   } else {
     ctx.file.result = result
   }
 }
 
 // Function to create the first processor.
-function unified() {
+function base() {
   var attachers = []
   var transformers = trough()
   var namespace = {}
@@ -80,7 +78,7 @@ function unified() {
 
   // Create a new processor based on the processor in the current scope.
   function processor() {
-    var destination = unified()
+    var destination = base()
     var index = -1
 
     while (++index < attachers.length) {
@@ -172,7 +170,7 @@ function unified() {
     if (value === null || value === undefined) {
       // Empty.
     } else if (typeof value === 'function') {
-      addPlugin.apply(null, arguments)
+      addPlugin(...arguments)
     } else if (typeof value === 'object') {
       if ('length' in value) {
         addList(value)
@@ -202,7 +200,7 @@ function unified() {
         addPlugin(value)
       } else if (typeof value === 'object') {
         if ('length' in value) {
-          addPlugin.apply(null, value)
+          addPlugin(...value)
         } else {
           addPreset(value)
         }
@@ -229,7 +227,7 @@ function unified() {
       var entry = find(plugin)
 
       if (entry) {
-        if (plain(entry[1]) && plain(value)) {
+        if (isPlainObj(entry[1]) && isPlainObj(value)) {
           value = extend(true, entry[1], value)
         }
 
@@ -355,7 +353,7 @@ function unified() {
     function executor(resolve, reject) {
       var file = vfile(doc)
 
-      pipeline.run(processor, {file: file}, done)
+      pipeline.run(processor, {file}, done)
 
       function done(error) {
         if (error) {
@@ -454,3 +452,7 @@ function assertDone(name, asyncName, complete) {
     )
   }
 }
+
+function vfile(doc) {
+  return doc instanceof VFile ? doc : new VFile(doc)
+}

package.json

@@ -36,6 +36,8 @@
     "Vse Mozhet Byt <vsemozhetbyt@gmail.com>",
     "Richard Littauer <richard.littauer@gmail.com>"
   ],
+  "sideEffects": false,
+  "type": "module",
   "types": "types/ts3.4/index.d.ts",
   "typesVersions": {
     ">=4.0": {
@@ -47,39 +49,34 @@
   "files": [
     "types/ts3.4/index.d.ts",
     "types/ts4.0/index.d.ts",
-    "index.js",
-    "lib"
+    "index.d.ts",
+    "index.js"
   ],
   "dependencies": {
-    "bail": "^1.0.0",
+    "bail": "^2.0.0",
     "extend": "^3.0.0",
     "is-buffer": "^2.0.0",
-    "is-plain-obj": "^2.0.0",
-    "trough": "^1.0.0",
-    "vfile": "^4.0.0"
+    "is-plain-obj": "^4.0.0",
+    "trough": "^2.0.0",
+    "vfile": "^5.0.0"
   },
   "devDependencies": {
-    "browserify": "^17.0.0",
     "c8": "^7.0.0",
     "dtslint": "^4.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
     "tape": "^5.0.0",
-    "tinyify": "^3.0.0",
-    "xo": "^0.38.0"
+    "xo": "^0.39.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
-    "build-bundle": "browserify index.js -s unified -o unified.js",
-    "build-mangle": "browserify index.js -s unified -p tinyify -o unified.min.js",
-    "build": "npm run build-bundle && npm run build-mangle",
-    "test-api": "node test",
-    "test-coverage": "c8 --check-coverage --lines 100 --functions 100 --branches 100 --reporter lcov tape test",
-    "test-types": "npm run test-types-3.4 && npm run test-types-4.0",
-    "test-types-3.4": "dtslint types/ts3.4",
-    "test-types-4.0": "dtslint types/ts4.0",
-    "test": "npm run format && npm run build && npm run test-coverage && npm run test-types"
+    "test-api": "node --conditions development test/index.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node --conditions development test/index.js",
+    "xxx-test-types": "npm run test-types-3.4 && npm run test-types-4.0",
+    "xxx-test-types-3.4": "dtslint types/ts3.4",
+    "xxx-test-types-4.0": "dtslint types/ts4.0",
+    "test": "npm run format && npm run test-coverage"
   },
   "prettier": {
     "tabWidth": 2,
@@ -91,8 +88,9 @@
   },
   "xo": {
     "prettier": true,
-    "esnext": false,
     "rules": {
+      "no-var": "off",
+      "prefer-arrow-callback": "off",
       "guard-for-in": "off",
       "no-unreachable-loop": "off",
       "unicorn/prefer-number-properties": "off",
@@ -101,8 +99,7 @@
       "unicorn/prefer-type-error": "off"
     },
     "ignores": [
-      "types",
-      "unified.js"
+      "types/"
     ]
   },
   "remarkConfig": {

readme.md

@@ -80,6 +80,9 @@ Support this effort and give back by sponsoring on [OpenCollective][collective]!
 
 ## 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
@@ -317,6 +320,9 @@ tree and discards the origin tree.
 
 ## API
 
+This package exports the following identifiers: `unified`.
+There is no default export.
+
 ### `processor()`
 
 [*Processor*][processors] describing how to *process* text.
@@ -638,7 +644,7 @@ The returned promise is rejected with a fatal error, or resolved with the
 processed [*file*][file].
 
 The parsed, transformed, and compiled value is exposed on
-[`file.contents`][vfile-contents] or `file.result` (see notes).
+[`file.value`][vfile-value] or `file.result` (see notes).
 
 ###### Note
 
@@ -651,7 +657,7 @@ unified typically compiles by serializing: most [*compiler*][compiler]s return
 Some compilers, such as the one configured with [`rehype-react`][rehype-react],
 return other values (in this case, a React tree).
 If you’re using a compiler that serializes, the result is available at
-`file.contents`.
+`file.value`.
 Otherwise, the result is available at `file.result`.
 
 ###### Example
@@ -758,7 +764,7 @@ An error is thrown if asynchronous [*plugin*][plugin]s are configured.
 ([`VFile`][vfile]) — Processed [*file*][file]
 
 The parsed, transformed, and compiled value is exposed on
-[`file.contents`][vfile-contents] or `file.result` (see notes).
+[`file.value`][vfile-value] or `file.result` (see notes).
 
 ###### Note
 
@@ -772,7 +778,7 @@ unified typically compiles by serializing: most [*compiler*][compiler]s return
 Some compilers, such as the one configured with [`rehype-react`][rehype-react],
 return other values (in this case, a React tree).
 If you’re using a compiler that serializes, the result is available at
-`file.contents`.
+`file.value`.
 Otherwise, the result is available at `file.result`.
 
 ###### Example
@@ -1285,7 +1291,7 @@ work on [`ware`][ware], as it was a huge initial inspiration.
 
 [vfile]: https://github.com/vfile/vfile
 
-[vfile-contents]: https://github.com/vfile/vfile#vfilecontents
+[vfile-value]: https://github.com/vfile/vfile#vfilevalue
 
 [vfile-utilities]: https://github.com/vfile/vfile#related-tools
 

test/async-function.js

@@ -1,11 +1,9 @@
-'use strict'
-
-var test = require('tape')
-var vfile = require('vfile')
-var unified = require('..')
+import test from 'tape'
+import {VFile} from 'vfile'
+import {unified} from '../index.js'
 
 test('async function transformer () {}', function (t) {
-  var givenFile = vfile('alpha')
+  var givenFile = new VFile('alpha')
   var givenNode = {type: 'bravo'}
   var modifiedNode = {type: 'charlie'}
 

test/core.js

@@ -1,7 +1,5 @@
-'use strict'
-
-var test = require('tape')
-var unified = require('..')
+import test from 'tape'
+import {unified} from '../index.js'
 
 test('unified()', function (t) {
   var count

test/data.js

@@ -1,7 +1,5 @@
-'use strict'
-
-var test = require('tape')
-var unified = require('..')
+import test from 'tape'
+import {unified} from '../index.js'
 
 test('data(key[, value])', function (t) {
   var processor = unified()

test/freeze.js

@@ -1,16 +1,14 @@
-'use strict'
-
-var test = require('tape')
-var simple = require('./util/simple.js')
-var unified = require('..')
+import test from 'tape'
+import {SimpleCompiler, SimpleParser} from './util/simple.js'
+import {unified} from '../index.js'
 
 test('freeze()', function (t) {
   var frozen = unified().use(config).freeze()
   var unfrozen = frozen()
 
   function config() {
-    this.Parser = simple.Parser
-    this.Compiler = simple.Compiler
+    this.Parser = SimpleParser
+    this.Compiler = SimpleCompiler
   }
 
   t.doesNotThrow(function () {

test/index.js

@@ -1,25 +1,11 @@
-'use strict'
-
 /* eslint-disable import/no-unassigned-import */
-require('./core.js')
-require('./freeze.js')
-require('./data.js')
-require('./use.js')
-require('./parse.js')
-require('./run.js')
-require('./stringify.js')
-require('./process.js')
-
-var asyncfunctions = false
-
-try {
-  eval('typeof async function() {}') // eslint-disable-line no-eval
-  asyncfunctions = true
-} catch (_) {}
-
-console.log('asyncfunctions:', asyncfunctions)
-if (asyncfunctions) {
-  require('./async-function.js')
-}
-
+import './core.js'
+import './freeze.js'
+import './data.js'
+import './use.js'
+import './parse.js'
+import './run.js'
+import './stringify.js'
+import './process.js'
+import './async-function.js'
 /* eslint-enable import/no-unassigned-import */

test/parse.js

@@ -1,7 +1,5 @@
-'use strict'
-
-var test = require('tape')
-var unified = require('..')
+import test from 'tape'
+import {unified} from '../index.js'
 
 test('parse(file)', function (t) {
   var processor = unified()