Add Typescript definition and require Node.js 10 (#1)

.gitignore

@@ -1 +1,3 @@
 node_modules
+package-lock.json
+yarn.lock

.npmrc

@@ -0,0 +1 @@
+package-lock=false

.travis.yml

@@ -1,7 +1,6 @@
-sudo: false
 language: node_js
+
 node_js:
-  - '6'
-  - '4'
-  - '0.12'
-  - '0.10'
+  - '14'
+  - '12'
+  - '10'

index.d.ts

@@ -0,0 +1,14 @@
+/**
+Randomize the order of items in an array
+
+@param array The array to shuffle.
+
+@example
+```
+const shuffled = arrayShuffle([1, 2, 3, 4, 5, 6]);
+//=> [3, 5, 4, 1, 2, 6]
+```
+*/
+declare function arrayShuffle<ArrayValueType>(array: readonly ArrayValueType[]): ArrayValueType[];
+
+export = arrayShuffle;

index.js

@@ -1,20 +1,16 @@
 'use strict';
-module.exports = function (arr) {
-	if (!Array.isArray(arr)) {
-		throw new TypeError('Expected Array, got ' + typeof arr);
+
+module.exports = array => {
+	if (!Array.isArray(array)) {
+		throw new TypeError(`Expected an array, got ${typeof array}`);
 	}
 
-	var rand;
-	var tmp;
-	var len = arr.length;
-	var ret = arr.slice();
+	array = [...array];
 
-	while (len) {
-		rand = Math.floor(Math.random() * len--);
-		tmp = ret[len];
-		ret[len] = ret[rand];
-		ret[rand] = tmp;
+	for (let index = array.length - 1; index > 0; index--) {
+		const newIndex = Math.floor(Math.random() * (index + 1));
+		[array[index], array[newIndex]] = [array[newIndex], array[index]];
 	}
 
-	return ret;
+	return array;
 };

index.test-d.ts

@@ -0,0 +1,6 @@
+import {expectType} from 'tsd';
+import arrayShuffle = require('.');
+
+const fixture = [1, 2, 3, 4, 5];
+
+expectType<number[]>(arrayShuffle(fixture));

package.json

@@ -10,27 +10,29 @@
     "url": "sindresorhus.com"
   },
   "engines": {
-    "node": ">=0.10.0"
+    "node": ">=10"
   },
   "scripts": {
-    "test": "xo && ava"
+    "test": "xo && ava && tsd"
   },
   "files": [
-    "index.js"
+    "index.js",
+    "index.d.ts"
   ],
   "keywords": [
     "array",
-    "arr",
     "list",
     "shuffle",
     "sort",
     "random",
     "rand",
     "fisher",
-    "yates"
+    "yates",
+    "durstenfeld"
   ],
   "devDependencies": {
-    "ava": "*",
-    "xo": "*"
+    "ava": "^3.13.0",
+    "tsd": "^0.13.1",
+    "xo": "^0.35.0"
   }
 }

readme.md

@@ -2,24 +2,27 @@
 
 > Randomize the order of items in an array
 
-Uses the [Fisher–Yates algorithm](https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle).
-
+Uses the [Durstenfeld algorithm](https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#The_modern_algorithm) based on the [Fisher–Yates algorithm](https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle).
 
 ## Install
 
 ```
-$ npm install --save array-shuffle
+$ npm install array-shuffle
 ```
 
-
 ## Usage
 
 ```js
 const shuffled = arrayShuffle([1, 2, 3, 4, 5, 6]);
 //=> [3, 5, 4, 1, 2, 6]
 ```
 
+## API
+
+### arrayShuffle(array)
+
+#### array
 
-## License
+Type: `array`
 
-MIT © [Sindre Sorhus](https://sindresorhus.com)
+The array to shuffle.

test.js

@@ -1,6 +1,6 @@
-import test from 'ava';
-import m from './';
+const test = require('ava');
+const arrayShuffle = require('.');
 
-test(t => {
-	t.notDeepEqual(m([1, 2, 3, 4, 5, 6]), [1, 2, 3, 4, 5, 6]);
+test('main', t => {
+	t.notDeepEqual(arrayShuffle([1, 2, 3, 4, 5, 6]), [1, 2, 3, 4, 5, 6]);
 });