Require Node.js 6, add TypeScript definition

.gitattributes

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

.gitignore

@@ -1 +1,2 @@
 node_modules
+yarn.lock

.npmrc

@@ -0,0 +1 @@
+package-lock=false

.travis.yml

@@ -1,3 +1,5 @@
 language: node_js
 node_js:
-  - 'node'
+  - '10'
+  - '8'
+  - '6'

index.d.ts

@@ -0,0 +1,9 @@
+/**
+ * Copy text to the clipboard.
+ *
+ * Must be called in response to a user gesture event, like `click` or `keyup`.
+ *
+ * @param text - The text to copy to clipboard.
+ * @returns Whether it succeeded to copy text.
+ */
+export default function copyTextToClipboard(text: string): boolean;

index.js

@@ -1,5 +1,5 @@
 'use strict';
-module.exports = input => {
+const copyTextToClipboard = input => {
 	const el = document.createElement('textarea');
 
 	el.value = input;
@@ -18,7 +18,7 @@ module.exports = input => {
 		originalRange = selection.getRangeAt(0);
 	}
 
-	document.body.appendChild(el);
+	document.body.appendChild(el); // eslint-disable-line unicorn/prefer-node-append
 	el.select();
 
 	// Explicit selection workaround for iOS
@@ -28,7 +28,7 @@ module.exports = input => {
 	let success = false;
 	try {
 		success = document.execCommand('copy');
-	} catch (err) {}
+	} catch (error) {}
 
 	document.body.removeChild(el);
 
@@ -39,3 +39,6 @@ module.exports = input => {
 
 	return success;
 };
+
+module.exports = copyTextToClipboard;
+module.exports.default = copyTextToClipboard;

index.test-d.ts

@@ -0,0 +1,4 @@
+import {expectType} from 'tsd-check';
+import copyTextToClipboard from '.';
+
+expectType<boolean>(copyTextToClipboard('🦄🌈'));

package.json

@@ -10,13 +10,14 @@
     "url": "sindresorhus.com"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=6"
   },
   "scripts": {
-    "test": "xo"
+    "test": "xo && tsd-check"
   },
   "files": [
-    "index.js"
+		"index.js",
+		"index.d.ts"
   ],
   "keywords": [
     "copy",
@@ -27,7 +28,8 @@
     "modern"
   ],
   "devDependencies": {
-    "xo": "*"
+    "tsd-check": "^0.3.0",
+    "xo": "^0.24.0"
   },
   "xo": {
     "envs": [