Use ESM

.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

index.js

@@ -1,2 +1 @@
-'use strict'
-module.exports = require('./lib/index.js')
+export {args} from './lib/index.js'

lib/index.js

@@ -1,12 +1,8 @@
-'use strict'
-
-var stream = require('stream')
-var engine = require('unified-engine')
-var chalk = require('chalk')
-var chokidar = require('chokidar')
-var options = require('./options.js')
-
-module.exports = start
+import stream from 'stream'
+import engine from 'unified-engine'
+import chalk from 'chalk'
+import chokidar from 'chokidar'
+import {options} from './options.js'
 
 var noop = Function.prototype
 
@@ -23,7 +19,7 @@ process.on('exit', onexit)
 process.on('uncaughtException', fail)
 
 // Start the CLI.
-function start(cliConfig) {
+export function args(cliConfig) {
   var config
   var output
   var watcher
@@ -142,9 +138,9 @@ function start(cliConfig) {
 
 // Print an error, optionally with stack.
 function fail(error, pretty) {
-  var message =
-    (pretty ? String(error).trim() : error.stack) ||
-    /* istanbul ignore next - Old versions of Node */ error
+  // Old versions of Node
+  /* c8 ignore next 1 */
+  var message = (pretty ? String(error).trim() : error.stack) || error
 
   exitStatus = 1
 

lib/options.js

@@ -1,13 +1,9 @@
-'use strict'
-
-var table = require('text-table')
-var camelcase = require('camelcase')
-var minimist = require('minimist')
-var json5 = require('json5')
-var fault = require('fault')
-var schema = require('./schema.json')
-
-module.exports = options
+import table from 'text-table'
+import camelcase from 'camelcase'
+import minimist from 'minimist'
+import json5 from 'json5'
+import fault from 'fault'
+import {schema} from './schema.js'
 
 // Schema for `minimist`.
 var minischema = {
@@ -24,7 +20,7 @@ while (++index < schema.length) {
 }
 
 // Parse CLI options.
-function options(flags, configuration) {
+export function options(flags, configuration) {
   var extension = configuration.extensions[0]
   var name = configuration.name
   var config = toCamelCase(minimist(flags, minischema))
@@ -243,6 +239,7 @@ function normalize(value) {
 
 // Flatten `values`.
 function flatten(values) {
+  // eslint-disable-next-line prefer-spread
   return [].concat.apply([], values)
 }
 

lib/schema.js

@@ -0,0 +1,161 @@
+export const schema = [
+  {
+    long: 'help',
+    description: 'output usage information',
+    short: 'h',
+    type: 'boolean',
+    default: false
+  },
+  {
+    long: 'version',
+    description: 'output version number',
+    short: 'v',
+    type: 'boolean',
+    default: false
+  },
+  {
+    long: 'output',
+    description: 'specify output location',
+    short: 'o',
+    value: '[path]'
+  },
+  {
+    long: 'rc-path',
+    description: 'specify configuration file',
+    short: 'r',
+    type: 'string',
+    value: '<path>'
+  },
+  {
+    long: 'ignore-path',
+    description: 'specify ignore file',
+    short: 'i',
+    type: 'string',
+    value: '<path>'
+  },
+  {
+    long: 'setting',
+    description: 'specify settings',
+    short: 's',
+    type: 'string',
+    value: '<settings>'
+  },
+  {
+    long: 'ext',
+    description: 'specify extensions',
+    short: 'e',
+    type: 'string',
+    value: '<extensions>'
+  },
+  {
+    long: 'use',
+    description: 'use plugins',
+    short: 'u',
+    type: 'string',
+    value: '<plugins>'
+  },
+  {
+    long: 'watch',
+    description: 'watch for changes and reprocess',
+    short: 'w',
+    type: 'boolean',
+    default: false
+  },
+  {
+    long: 'quiet',
+    description: 'output only warnings and errors',
+    short: 'q',
+    type: 'boolean',
+    default: false
+  },
+  {
+    long: 'silent',
+    description: 'output only errors',
+    short: 'S',
+    type: 'boolean',
+    default: false
+  },
+  {
+    long: 'frail',
+    description: 'exit with 1 on warnings',
+    short: 'f',
+    type: 'boolean',
+    default: false
+  },
+  {
+    long: 'tree',
+    description: 'specify input and output as syntax tree',
+    short: 't',
+    type: 'boolean',
+    default: false
+  },
+  {
+    long: 'report',
+    description: 'specify reporter',
+    type: 'string',
+    value: '<reporter>'
+  },
+  {
+    long: 'file-path',
+    description: 'specify path to process as',
+    type: 'string',
+    value: '<path>'
+  },
+  {
+    long: 'ignore-path-resolve-from',
+    description: 'resolve patterns in `ignore-path` from its directory or cwd',
+    type: 'string',
+    value: 'dir|cwd',
+    default: 'dir'
+  },
+  {
+    long: 'ignore-pattern',
+    description: 'specify ignore patterns',
+    type: 'string',
+    value: '<globs>'
+  },
+  {
+    long: 'silently-ignore',
+    description: 'do not fail when given ignored files',
+    type: 'boolean'
+  },
+  {
+    long: 'tree-in',
+    description: 'specify input as syntax tree',
+    type: 'boolean'
+  },
+  {
+    long: 'tree-out',
+    description: 'output syntax tree',
+    type: 'boolean'
+  },
+  {
+    long: 'inspect',
+    description: 'output formatted syntax tree',
+    type: 'boolean'
+  },
+  {
+    long: 'stdout',
+    description: 'specify writing to stdout',
+    type: 'boolean',
+    truelike: true
+  },
+  {
+    long: 'color',
+    description: 'specify color in report',
+    type: 'boolean',
+    default: true
+  },
+  {
+    long: 'config',
+    description: 'search for configuration files',
+    type: 'boolean',
+    default: true
+  },
+  {
+    long: 'ignore',
+    description: 'search for ignore files',
+    type: 'boolean',
+    default: true
+  }
+]