Add TypeScript definition

index.d.ts

@@ -0,0 +1,37 @@
+interface ClearablePromise<T> extends Promise<T> {
+	/**
+	 * Clears the delay and settles the promise.
+	 */
+	clear(): void;
+}
+
+declare const delay: {
+	/**
+	 * Create a promise which resolves after the specified `milliseconds`.
+	 *
+	 * @param milliseconds - Milliseconds to delay the promise.
+	 * @returns A promise which resolves after the specified `milliseconds`.
+	 */
+	(milliseconds: number): ClearablePromise<void>;
+
+	/**
+	 * Create a promise which resolves after the specified `milliseconds`.
+	 *
+	 * @param milliseconds - Milliseconds to delay the promise.
+	 * @param value - Value to resolve in the returned promise.
+	 * @returns A promise which resolves after the specified `milliseconds`.
+	 */
+	<T>(milliseconds: number, value: T): ClearablePromise<T>;
+
+	/**
+	 * Create a promise which rejects after the specified `milliseconds`.
+	 *
+	 * @param milliseconds - Milliseconds to delay the promise.
+	 * @param reason - Value to reject in the returned promise.
+	 * @returns A promise which rejects after the specified `milliseconds`.
+	 */
+	// TODO: Allow providing reason type after https://github.com/Microsoft/TypeScript/issues/5413 will be resolved.
+	reject(milliseconds: number, reason?: any): ClearablePromise<never>;
+};
+
+export default delay;

index.js

@@ -20,5 +20,7 @@ const createDelay = willResolve => (ms, value) => {
 	return delayPromise;
 };
 
-module.exports = createDelay(true);
-module.exports.reject = createDelay(false);
+const delay = createDelay(true);
+delay.reject = createDelay(false);
+module.exports = delay;
+module.exports.default = delay;

package.json

@@ -16,7 +16,8 @@
 		"test": "xo && ava"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"promise",