Add TypeScript definition (#13)

index.d.ts

@@ -0,0 +1,55 @@
+declare namespace cliTruncate {
+	interface Options {
+		/**
+		Position to truncate the string.
+
+		@default 'end'
+		*/
+		readonly position?: 'start' | 'middle' | 'end';
+	}
+}
+
+/**
+Truncate a string to a specific width in the terminal.
+
+@param input - Text to truncate.
+@param columns - Columns to occupy in the terminal.
+
+@example
+```
+import cliTruncate = require('cli-truncate');
+
+cliTruncate('unicorn', 4);
+//=> 'uni…'
+
+// Truncate at different positions
+cliTruncate('unicorn', 4, {position: 'start'});
+//=> '…orn'
+
+cliTruncate('unicorn', 4, {position: 'middle'});
+//=> 'un…n'
+
+cliTruncate('\u001B[31municorn\u001B[39m', 4);
+//=> '\u001B[31muni\u001B[39m…'
+
+// Truncate Unicode surrogate pairs
+cliTruncate('uni\uD83C\uDE00corn', 5);
+//=> 'uni\uD83C\uDE00…'
+
+// Truncate fullwidth characters
+cliTruncate('안녕하세요', 3);
+//=> '안…'
+
+// Truncate the paragraph to the terminal width
+const paragraph = 'Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa.';
+cliTruncate(paragraph, process.stdout.columns));
+//=> 'Lorem ipsum dolor sit amet, consectetuer adipiscing…'
+```
+*/
+declare function cliTruncate(
+	input: string,
+	columns: number,
+	options?: cliTruncate.Options
+): string;
+
+export = cliTruncate;

index.test-d.ts

@@ -0,0 +1,7 @@
+import {expectType} from 'tsd';
+import cliTruncate = require('.');
+
+expectType<string>(cliTruncate('unicorn', 4));
+expectType<string>(cliTruncate('unicorn', 4, {position: 'start'}));
+expectType<string>(cliTruncate('unicorn', 4, {position: 'middle'}));
+expectType<string>(cliTruncate('unicorn', 4, {position: 'end'}));

package.json

@@ -13,10 +13,11 @@
 		"node": ">=8"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"truncate",
@@ -37,6 +38,7 @@
 	},
 	"devDependencies": {
 		"ava": "^1.4.1",
+		"tsd": "^0.7.2",
 		"xo": "^0.24.0"
 	}
 }