Add TypeScript definition (#32)

index.d.ts

@@ -0,0 +1,40 @@
+declare namespace isReachable {
+	interface Options {
+		/**
+		Timeout in milliseconds after which a request is considered failed.
+
+		@default 5000
+		*/
+		readonly timeout?: number;
+	}
+}
+
+/**
+Check if servers are reachable.
+
+The Node.js version will do a TCP handshake with the target's port. It attempts to detect cases where a router redirects the request to itself.
+
+The browser version is limited by the fact that browsers cannot connect to arbitrary ports. It only supports HTTP and HTTPS and the check relies on the `/favicon.ico` path being present.
+
+@param targets - One or more targets to check. Can either be a full [URL](https://nodejs.org/api/url.html) like `https://hostname`, `hostname:port` or just `hostname`. When the protocol is missing from a target `http` is assumed. [Well-known protocols](http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml) are supported (e.g. `ftp://`, `mysql://`, `redis://` and more).
+@returns Whether any of the `targets` are reachable.
+
+@example
+```
+import isReachable = require('is-reachable');
+
+(async () => {
+	console.log(await isReachable('sindresorhus.com'));
+	//=> true
+
+	console.log(await isReachable('google.com:80'));
+	//=> true
+})();
+```
+*/
+declare function isReachable(
+	targets: string | readonly string[],
+	options?: isReachable.Options
+): Promise<boolean>;
+
+export = isReachable;

index.test-d.ts

@@ -0,0 +1,6 @@
+import {expectType} from 'tsd';
+import isReachable = require('.');
+
+const options: isReachable.Options = {};
+expectType<Promise<boolean>>(isReachable('sindresorhus.com'));
+expectType<Promise<boolean>>(isReachable('google.com:80', {timeout: 10}));

package.json

@@ -16,10 +16,11 @@
 		"node": ">=8"
 	},
 	"scripts": {
-		"test": "xo && ava test.js"
+		"test": "xo && ava test.js && tsd"
 	},
 	"files": [
 		"index.js",
+		"index.d.ts",
 		"browser.js"
 	],
 	"keywords": [
@@ -41,19 +42,20 @@
 		"socket"
 	],
 	"dependencies": {
-		"arrify": "^1.0.1",
-		"got": "^9.3.2",
-		"is-port-reachable": "^2.0.0",
-		"p-any": "^1.1.0",
-		"p-timeout": "^2.0.1",
-		"port-numbers": "^4.0.4",
+		"arrify": "^2.0.1",
+		"got": "^9.6.0",
+		"is-port-reachable": "^2.0.1",
+		"p-any": "^2.1.0",
+		"p-timeout": "^3.1.0",
+		"port-numbers": "^4.0.7",
 		"prepend-http": "^2.0.0",
 		"router-ips": "^1.0.0",
-		"url-parse": "^1.4.4"
+		"url-parse": "^1.4.6"
 	},
 	"devDependencies": {
-		"ava": "^0.25.0",
-		"xo": "^0.23.0"
+		"ava": "^1.4.1",
+		"tsd": "^0.7.2",
+		"xo": "^0.24.0"
 	},
 	"browser": "browser.js"
 }

readme.md

@@ -47,7 +47,7 @@ One or more targets to check. Can either be a full [URL](https://nodejs.org/api/
 
 #### options
 
-Type: `Object`
+Type: `object`
 
 ##### timeout
 
@@ -70,4 +70,4 @@ Timeout in milliseconds after which a request is considered failed. Default: `50
 
 MIT © [Sindre Sorhus](https://sindresorhus.com)
 
-[Well-known protocols]: http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml
+[Well-known protocols]: https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml