Require Node.js 8, add TypeScript definition

.gitattributes

@@ -1,2 +1 @@
-* text=auto
-*.js text eol=lf
+* text=auto eol=lf

.travis.yml

@@ -1,5 +1,4 @@
 language: node_js
 node_js:
+  - '10'
   - '8'
-  - '6'
-  - '4'

index.d.ts

@@ -0,0 +1,44 @@
+declare namespace indentString {
+	interface Options {
+		/**
+		String to use for the indent.
+
+		@default ' '
+		*/
+		readonly indent?: string;
+
+		/**
+		Also indent empty lines.
+
+		@default false
+		*/
+		readonly includeEmptyLines?: boolean;
+	}
+}
+
+/**
+Indent each line in a string.
+
+@param string - String you want to indent.
+@param count - How many times you want `options.indent` repeated. Default: `1`.
+
+@example
+```
+import indentString = require('indent-string');
+
+indentString('Unicorns\nRainbows', 4);
+//=> '    Unicorns'
+//=> '    Rainbows'
+
+indentString('Unicorns\nRainbows', 4, {indent: '♥'});
+//=> '♥♥♥♥Unicorns'
+//=> '♥♥♥♥Rainbows'
+```
+*/
+declare function indentString(
+	string: string,
+	count?: number,
+	options?: indentString.Options
+): string;
+
+export = indentString;

index.js

@@ -1,27 +1,35 @@
 'use strict';
-module.exports = (str, count, opts) => {
-	// Support older versions: use the third parameter as options.indent
-	// TODO: Remove the workaround in the next major version
-	const options = typeof opts === 'object' ? Object.assign({indent: ' '}, opts) : {indent: opts || ' '};
-	count = count === undefined ? 1 : count;
 
-	if (typeof str !== 'string') {
-		throw new TypeError(`Expected \`input\` to be a \`string\`, got \`${typeof str}\``);
+module.exports = (string, count = 1, options) => {
+	options = {
+		indent: ' ',
+		includeEmptyLines: false,
+		...options
+	};
+
+	if (typeof string !== 'string') {
+		throw new TypeError(
+			`Expected \`input\` to be a \`string\`, got \`${typeof string}\``
+		);
 	}
 
 	if (typeof count !== 'number') {
-		throw new TypeError(`Expected \`count\` to be a \`number\`, got \`${typeof count}\``);
+		throw new TypeError(
+			`Expected \`count\` to be a \`number\`, got \`${typeof count}\``
+		);
 	}
 
 	if (typeof options.indent !== 'string') {
-		throw new TypeError(`Expected \`options.indent\` to be a \`string\`, got \`${typeof options.indent}\``);
+		throw new TypeError(
+			`Expected \`options.indent\` to be a \`string\`, got \`${typeof options.indent}\``
+		);
 	}
 
 	if (count === 0) {
-		return str;
+		return string;
 	}
 
-	const regex = options.includeEmptyLines ? /^/mg : /^(?!\s*$)/mg;
-	return str.replace(regex, options.indent.repeat(count));
-}
-;
+	const regex = options.includeEmptyLines ? /^/gm : /^(?!\s*$)/gm;
+
+	return string.replace(regex, options.indent.repeat(count));
+};

index.test-d.ts

@@ -0,0 +1,9 @@
+import {expectType} from 'tsd';
+import indentString = require('.');
+
+expectType<string>(indentString('Unicorns\nRainbows'));
+expectType<string>(indentString('Unicorns\nRainbows', 4));
+expectType<string>(indentString('Unicorns\nRainbows', 4, {indent: '♥'}));
+expectType<string>(
+	indentString('Unicorns\nRainbows', 4, {includeEmptyLines: true})
+);

package.json

@@ -1,36 +1,38 @@
 {
-  "name": "indent-string",
-  "version": "3.2.0",
-  "description": "Indent each line in a string",
-  "license": "MIT",
-  "repository": "sindresorhus/indent-string",
-  "author": {
-    "name": "Sindre Sorhus",
-    "email": "[email protected]",
-    "url": "sindresorhus.com"
-  },
-  "engines": {
-    "node": ">=4"
-  },
-  "scripts": {
-    "test": "xo && ava"
-  },
-  "files": [
-    "index.js"
-  ],
-  "keywords": [
-    "indent",
-    "string",
-    "str",
-    "pad",
-    "align",
-    "line",
-    "text",
-    "each",
-    "every"
-  ],
-  "devDependencies": {
-    "ava": "*",
-    "xo": "*"
-  }
+	"name": "indent-string",
+	"version": "3.2.0",
+	"description": "Indent each line in a string",
+	"license": "MIT",
+	"repository": "sindresorhus/indent-string",
+	"author": {
+		"name": "Sindre Sorhus",
+		"email": "[email protected]",
+		"url": "sindresorhus.com"
+	},
+	"engines": {
+		"node": ">=8"
+	},
+	"scripts": {
+		"test": "xo && ava && tsd"
+	},
+	"files": [
+		"index.js",
+		"index.d.ts"
+	],
+	"keywords": [
+		"indent",
+		"string",
+		"str",
+		"pad",
+		"align",
+		"line",
+		"text",
+		"each",
+		"every"
+	],
+	"devDependencies": {
+		"ava": "^1.4.1",
+		"tsd": "^0.7.2",
+		"xo": "^0.24.0"
+	}
 }

readme.md

@@ -40,11 +40,11 @@ String you want to indent.
 Type: `number`<br>
 Default: `1`
 
-How many times you want `indent` repeated.
+How many times you want `options.indent` repeated.
 
 #### options
 
-Type: `Object`<br>
+Type: `object`<br>
 
 ##### indent