From 8928ccab1e613f9e606c4f2a203bb64bed7444fb Mon Sep 17 00:00:00 2001
From: vigan-abd <vigan.abd@gmail.com>
Date: Thu, 2 Nov 2023 15:03:13 +0100
Subject: [PATCH 1/2] feat: shuffle function

---
 CHANGELOG       |  3 +++
 README.md       |  1 +
 index.d.ts      |  1 +
 index.js        |  4 +++-
 package.json    |  2 +-
 src/shuffle.js  | 22 ++++++++++++++++++++++
 test/shuffle.js | 18 ++++++++++++++++++
 7 files changed, 49 insertions(+), 2 deletions(-)
 create mode 100644 src/shuffle.js
 create mode 100644 test/shuffle.js

diff --git a/CHANGELOG b/CHANGELOG
index f06bc0f..d8de468 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,6 @@
+# 1.5.0
+- feat: shuffle
+
 # 1.4.0
 - feat: isObject
 
diff --git a/README.md b/README.md
index f201b3d..748c46a 100644
--- a/README.md
+++ b/README.md
@@ -18,3 +18,4 @@ Currently supported utils:
 - `omitBy` -  provides new object that omits only specific fields of source object depending on predicate function filter
 - `pick` - provides new object that picks only specific fields of source object
 - `pickBy` -  provides new object that picks only specific fields of source object depending on predicate function filter
+- `shuffle` - performs pseudo random shuffle on clone of the array
diff --git a/index.d.ts b/index.d.ts
index eec0684..d969ecd 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -13,3 +13,4 @@ export function omit(obj: Object, keys: Array<string>): Object
 export function omitBy(obj: Object, predicate: (val: any, key: string) => boolean): Object
 export function pick(obj: Object, keys: Array<string>): Object
 export function pickBy(obj: Object, predicate: (val: any, key: string) => boolean): Object
+export function shuffle<T>(array: Array<T>): Array<T>
diff --git a/index.js b/index.js
index 81a124c..319702a 100644
--- a/index.js
+++ b/index.js
@@ -15,6 +15,7 @@ const omit = require('./src/omit')
 const omitBy = require('./src/omitBy')
 const pick = require('./src/pick')
 const pickBy = require('./src/pickBy')
+const shuffle = require('./src/shuffle')
 
 module.exports = {
   camelize,
@@ -31,5 +32,6 @@ module.exports = {
   omit,
   omitBy,
   pick,
-  pickBy
+  pickBy,
+  shuffle
 }
diff --git a/package.json b/package.json
index f16b48e..45afed0 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@bitfinex/lib-js-util-base",
-  "version": "1.4.0",
+  "version": "1.5.0",
   "description": "general utils",
   "main": "index.js",
   "scripts": {
diff --git a/src/shuffle.js b/src/shuffle.js
new file mode 100644
index 0000000..e28b7a2
--- /dev/null
+++ b/src/shuffle.js
@@ -0,0 +1,22 @@
+'use strict'
+
+/**
+ * Performs pseudo random shuffles on clone of the array
+ *
+ * @param {Array<any>} array
+ * @returns {Array<any>}
+ */
+const shuffle = (array) => {
+  const clone = [...array]
+  const length = clone.length
+  for (let i = 0; i < length; i++) {
+    const mov = Math.floor(Math.random() * length)
+    const tmp = clone[mov]
+    clone[mov] = clone[i]
+    clone[i] = tmp
+  }
+
+  return clone
+}
+
+module.exports = shuffle
diff --git a/test/shuffle.js b/test/shuffle.js
new file mode 100644
index 0000000..817654e
--- /dev/null
+++ b/test/shuffle.js
@@ -0,0 +1,18 @@
+'use strict'
+
+/* eslint-env mocha */
+
+const assert = require('assert')
+const { shuffle } = require('../index')
+
+describe('shuffle', () => {
+  const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+
+  it('should return a new array', () => {
+    assert.ok(shuffle(array).some((x, i) => array[i] !== x))
+  })
+
+  it('should contain the same elements after a collection is shuffled', () => {
+    assert.deepStrictEqual(shuffle(array).sort((a, b) => a - b), array)
+  })
+})

From 1aa1b9bb787a48789d8caa829d16ce79af585c17 Mon Sep 17 00:00:00 2001
From: vigan-abd <vigan.abd@gmail.com>
Date: Thu, 2 Nov 2023 16:45:38 +0100
Subject: [PATCH 2/2] replace shuffle

---
 src/shuffle.js | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/shuffle.js b/src/shuffle.js
index e28b7a2..e8e9ecb 100644
--- a/src/shuffle.js
+++ b/src/shuffle.js
@@ -9,11 +9,9 @@
 const shuffle = (array) => {
   const clone = [...array]
   const length = clone.length
-  for (let i = 0; i < length; i++) {
-    const mov = Math.floor(Math.random() * length)
-    const tmp = clone[mov]
-    clone[mov] = clone[i]
-    clone[i] = tmp
+  for (let i = length - 1; i > 0; i--) {
+    const index = Math.floor(Math.random() * (i + 1)); // random index from 0 to i
+    [clone[i], clone[index]] = [clone[index], clone[i]] // swap elements
   }
 
   return clone