Add TypeScript definition (#7)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

index.d.ts

@@ -0,0 +1,26 @@
+/**
+Returns an array filled with the specified input.
+
+@param value - The value to fill the array with.
+@param count - The number of items to fill the array with.
+
+@example
+```
+import filledArray from 'filled-array';
+
+filledArray('x', 3);
+//=> ['x', 'x', 'x']
+
+filledArray(0, 3);
+//=> [0, 0, 0]
+
+filledArray(index => {
+	return (++index % 3 ? '' : 'Fizz') + (index % 5 ? '' : 'Buzz') || index;
+}, 15);
+//=> [1, 2, 'Fizz', 4, 'Buzz', 'Fizz', 7, 8, 'Fizz', 'Buzz', 11, 'Fizz', 13, 14, 'FizzBuzz']
+```
+*/
+export default function filledArray<T>(
+	value: T | ((index: number, count: number, currentArray: T[]) => T),
+	count: number
+): T[];

index.test-d.ts

@@ -0,0 +1,6 @@
+import {expectType} from 'tsd';
+import filledArray from './index.js';
+
+expectType<string[]>(filledArray('x', 3));
+expectType<number[]>(filledArray(0, 3));
+expectType<string[]>(filledArray(index => `Hey ${index}`, 3));

package.json

@@ -16,11 +16,12 @@
 		"node": ">=12"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd"
 	},
 	"files": [
-		"index.js"
-	],
+ 		"index.js",
+		"index.d.ts"
+ 	],
 	"keywords": [
 		"array",
 		"elements",
@@ -33,6 +34,7 @@
 	],
 	"devDependencies": {
 		"ava": "^4.0.0",
+		"tsd": "^0.19.1",
 		"xo": "^0.47.0"
 	}
 }