Document ES Modules usage (#147)

.travis.yml

@@ -1,4 +1,5 @@
 language: node_js
 node_js:
+  - '14'
   - '12'
   - '10'

estest/index.js

@@ -0,0 +1,24 @@
+import {createRequire} from 'module';
+
+const meow = createRequire(import.meta.url)('../index.js');
+
+meow(`
+	Usage
+	  $ estest <input>
+
+	Options
+	  --rainbow, -r  Include a rainbow
+
+	Examples
+	  $ estest unicorns --rainbow
+	  🌈 unicorns 🌈
+`,
+	{
+		flags: {
+			rainbow: {
+				type: 'boolean',
+				alias: 'r'
+			}
+		}
+	}
+);

estest/package.json

@@ -0,0 +1,5 @@
+{
+	"name": "estest",
+	"type": "module",
+	"version": "1.2.3"
+}

package.json

@@ -63,6 +63,9 @@
 		"rules": {
 			"unicorn/no-process-exit": "off",
 			"node/no-unsupported-features/es-syntax": "off"
-		}
+		},
+		"ignores": [
+			"estest/index.js"
+		]
 	}
 }

readme.md

@@ -26,6 +26,8 @@ $ npm install meow
 $ ./foo-app.js unicorns --rainbow
 ```
 
+**CommonJS**
+
 ```js
 #!/usr/bin/env node
 'use strict';
@@ -61,6 +63,44 @@ const cli = meow(`
 foo(cli.input[0], cli.flags);
 ```
 
+**ES Modules**
+
+```js
+#!/usr/bin/env node
+import {createRequire} from 'module';
+import foo from './lib/index.js';
+
+const meow = createRequire(import.meta.url)('meow');
+
+const cli = meow(`
+	Usage
+	  $ foo <input>
+
+	Options
+	  --rainbow, -r  Include a rainbow
+
+	Examples
+	  $ foo unicorns --rainbow
+	  🌈 unicorns 🌈
+`, {
+	flags: {
+		rainbow: {
+			type: 'boolean',
+			alias: 'r'
+		}
+	}
+});
+/*
+{
+	input: ['unicorns'],
+	flags: {rainbow: true},
+	...
+}
+*/
+
+foo(cli.input[0], cli.flags);
+```
+
 ## API
 
 ### meow(helpText, options?)

test.js

@@ -1,9 +1,12 @@
 import test from 'ava';
 import indentString from 'indent-string';
 import execa from 'execa';
+import path from 'path';
 import pkg from './package.json';
 import meow from '.';
 
+const NODE_MAJOR_VERSION = process.versions.node.split('.')[0];
+
 test('return object', t => {
 	const cli = meow({
 		argv: ['foo', '--foo-bar', '-u', 'cat', '--', 'unicorn', 'cake'],
@@ -307,3 +310,16 @@ test('supports `number` flag type - throws on incorrect default value', t => {
 		});
 	});
 });
+
+if (NODE_MAJOR_VERSION >= 14) {
+	test('supports es modules', async t => {
+		try {
+			const {stdout} = await execa('node', ['index.js', '--version'], {
+				cwd: path.join(__dirname, 'estest')
+			});
+			t.regex(stdout, /1.2.3/);
+		} catch (error) {
+			t.is(error, undefined);
+		}
+	});
+}