Add TypeScript definition (#28)

index.d.ts

@@ -0,0 +1,4 @@
+/**
+Strip [ANSI escape codes](https://en.wikipedia.org/wiki/ANSI_escape_code).
+*/
+export default function stripAnsi(str: string): string;

index.js

@@ -1,4 +1,7 @@
 'use strict';
 const ansiRegex = require('ansi-regex');
 
-module.exports = input => typeof input === 'string' ? input.replace(ansiRegex(), '') : input;
+const stripAnsi = input => typeof input === 'string' ? input.replace(ansiRegex(), '') : input;
+
+module.exports = stripAnsi;
+module.exports.default = stripAnsi;

index.test-d.ts

@@ -0,0 +1,4 @@
+import {expectType} from 'tsd-check';
+import stripAnsi from '.';
+
+expectType<string>(stripAnsi('\u001b[4mcake\u001b[0m'));

package.json

@@ -13,10 +13,11 @@
 		"node": ">=6"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd-check"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"strip",
@@ -46,7 +47,8 @@
 		"ansi-regex": "^4.1.0"
 	},
 	"devDependencies": {
-		"ava": "^0.25.0",
-		"xo": "^0.23.0"
+		"ava": "^1.3.1",
+		"tsd-check": "^0.5.0",
+		"xo": "^0.24.0"
 	}
 }