Require Node.js 8, add TypeScript definition (#7)

.gitattributes

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

.travis.yml

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

index.d.ts

@@ -0,0 +1,12 @@
+/**
+ * Check if your code is running as an [npm](https://docs.npmjs.com/misc/scripts) or [yarn](https://yarnpkg.com/lang/en/docs/cli/run/) script.
+ *
+ * @example
+ *
+ * import {isNpm} from 'isNpm';
+ *
+ * if (isNpm) {
+ * 	console.log('Running as a npm script!');
+ * }
+ */
+export const isNpm: boolean;

index.js

@@ -1,4 +1,9 @@
 'use strict';
-module.exports = 'npm_config_username' in process.env ||
+
+const isNpm =
+	'npm_config_username' in process.env ||
 	'npm_package_name' in process.env ||
 	'npm_config_heading' in process.env;
+
+// TODO: This named export should be replaced by a default export as soon as we move to ES modules
+exports.isNpm = isNpm;

index.test-d.ts

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

package.json

@@ -10,13 +10,14 @@
 		"url": "sindresorhus.com"
 	},
 	"engines": {
-		"node": ">=6"
+		"node": ">=8"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd-check"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"npm",
@@ -29,7 +30,8 @@
 		"script"
 	],
 	"devDependencies": {
-		"ava": "*",
-		"xo": "*"
+		"ava": "^1.3.1",
+		"tsd-check": "^0.3.0",
+		"xo": "^0.24.0"
 	}
 }

readme.md

@@ -13,7 +13,7 @@ $ npm install is-npm
 ## Usage
 
 ```js
-const isNpm = require('is-npm');
+const {isNpm} = require('is-npm');
 
 console.log(isNpm);
 ```

test.js

@@ -1,6 +1,6 @@
 import test from 'ava';
-import m from '.';
+import {isNpm} from '.';
 
 test('main', t => {
-	t.true(m);
+	t.true(isNpm);
 });