Add TypeScript typings

index.d.ts

@@ -0,0 +1,43 @@
+export interface IOptions {
+	/**
+	 * Directory to start from.
+	 * @default process.cwd()
+	 */
+	cwd: string;
+}
+
+/**
+ * Returns a `Promise` for either the filepath or `null` if it couldn't be found.
+ *
+ * @param filename - Filename of the file to find.
+ */
+declare function findUp(
+	filename: string,
+	options?: IOptions,
+): Promise<string | null>;
+/**
+ * Returns a `Promise` for either the first filepath found (by respecting the order) or `null` if none could be found.
+ *
+ * @param filename - Filename of the file to find.
+ */
+declare function findUp(
+	filename: string[],
+	options?: IOptions,
+): Promise<string | null>;
+
+declare namespace findUp {
+	/**
+	 * Returns a filepath or null.
+	 *
+	 * @param filename - Filename of the file to find.
+	 */
+	function sync(filename: string, options?: IOptions): string | null;
+	/**
+	 * Returns the first filepath found (by respecting the order) or null.
+	 *
+	 * @param filename - Filename of the file to find.
+	 */
+	function sync(filename: string[], options?: IOptions): string | null;
+}
+
+export default findUp;

index.test-d.ts

@@ -0,0 +1,42 @@
+import { expectType } from 'tsd-check';
+import findUp from '.';
+
+(async () => {
+	let path = await findUp('package.json');
+	if (typeof path === 'string') {
+		expectType<string>(path);
+	} else {
+		expectType<null>(path);
+	}
+	path = await findUp('package.json', { cwd: './' });
+	if (typeof path === 'string') {
+		expectType<string>(path);
+	} else {
+		expectType<null>(path);
+	}
+	path = await findUp(['package.json']);
+	if (typeof path === 'string') {
+		expectType<string>(path);
+	} else {
+		expectType<null>(path);
+	}
+
+	path = findUp.sync('package.json');
+	if (typeof path === 'string') {
+		expectType<string>(path);
+	} else {
+		expectType<null>(path);
+	}
+	path = findUp.sync('package.json', { cwd: './' });
+	if (typeof path === 'string') {
+		expectType<string>(path);
+	} else {
+		expectType<null>(path);
+	}
+	path = findUp.sync(['package.json']);
+	if (typeof path === 'string') {
+		expectType<string>(path);
+	} else {
+		expectType<null>(path);
+	}
+})();

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": [
 		"find",
@@ -45,6 +46,7 @@
 	"devDependencies": {
 		"ava": "*",
 		"tempy": "^0.2.1",
+		"tsd-check": "^0.2.1",
 		"xo": "*"
 	}
 }