Add TypeScript definition (#12)

.gitattributes

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

.travis.yml

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

index.d.ts

@@ -0,0 +1,37 @@
+/**
+Run some code when the process exits.
+
+The `process.on('exit')` event doesn't catch all the ways a process can exit.
+
+This package is useful for cleaning up before exiting.
+
+@param callback - The callback to execute when the process exits.
+@returns A function that removes the hook when called.
+
+@example
+```
+import exitHook = require('exit-hook');
+
+exitHook(() => {
+	console.log('Exiting');
+});
+
+// You can add multiple hooks, even across files
+exitHook(() => {
+	console.log('Exiting 2');
+});
+
+throw new Error('🦄');
+
+//=> 'Exiting'
+//=> 'Exiting 2'
+
+// Removing an exit hook:
+const unsubscribe = exitHook(() => {});
+
+unsubscribe();
+```
+*/
+declare function exitHook(callback: () => void): () => void;
+
+export = exitHook;

index.test-d.ts

@@ -0,0 +1,7 @@
+import {expectType} from 'tsd';
+import exitHook = require('.');
+
+const unsubscribe = exitHook(() => {});
+
+expectType<() => void>(unsubscribe);
+unsubscribe();

package.json

@@ -13,10 +13,11 @@
 		"node": ">=6"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"exit",
@@ -35,8 +36,9 @@
 		"signal"
 	],
 	"devDependencies": {
-		"ava": "*",
-		"execa": "^0.10.0",
-		"xo": "*"
+		"ava": "^1.4.1",
+		"execa": "^1.0.0",
+		"tsd": "^0.7.2",
+		"xo": "^0.24.0"
 	}
 }

readme.md

@@ -47,6 +47,19 @@ unsubscribe();
 ```
 
 
+## API
+
+### exitHook(callback)
+
+Returns a function that removes the hook when called.
+
+#### callback
+
+Type: `Function`
+
+The callback to execute when the process exits.
+
+
 ## License
 
 MIT © [Sindre Sorhus](https://sindresorhus.com)