feat: add shuffle

src/index.ts

@@ -30,4 +30,5 @@ export { default as noop } from './noop'
 export { default as parseCssValue } from './parseCssValue'
 export { default as reduce } from './reduce'
 export { default as repeat } from './repeat'
+export { default as shuffle } from './shuffle'
 export { default as supportPassiveEventListener } from './supportPassiveEventListener'

src/shuffle.ts

@@ -0,0 +1,20 @@
+/**
+ * 打乱一个数组。
+ *
+ * @param arr 要打乱的数组
+ * @returns 打乱后的数组
+ * @see https://gaohaoyang.github.io/2016/10/16/shuffle-algorithm/
+ */
+export default function shuffle<T>(arr: T[]): T[] {
+  if (!Array.isArray(arr)) {
+    return arr
+  }
+  const newArr = arr.slice()
+  for (let i = newArr.length - 1; i >= 0; i--) {
+    const randomIndex = Math.floor(Math.random() * (i + 1))
+    const itemAtIndex = newArr[randomIndex]
+    newArr[randomIndex] = newArr[i]
+    newArr[i] = itemAtIndex
+  }
+  return newArr
+}

test/index.test.ts

@@ -540,3 +540,26 @@ describe('cssTransform', () => {
     expect(el.style.transition).toBe('none')
   })
 })
+
+describe('shuffle', () => {
+  test('非数组原样返回', () => {
+    expect(vtils.shuffle(1 as any)).toEqual(1)
+    expect(vtils.shuffle({} as any)).toEqual({})
+    expect(vtils.shuffle(false as any)).toEqual(false)
+  })
+  test('打乱数组', () => {
+    const arr1 = [1, 2, 3]
+    for (let i = 0; i < 1000; i++) {
+      expect([
+        [1, 2, 3],
+        [1, 3, 2],
+        [2, 1, 3],
+        [2, 3, 1],
+        [3, 1, 2],
+        [3, 2, 1]
+      ]).toContainEqual(vtils.shuffle(arr1))
+    }
+    const arr2 = [1, 2, 3, '&', null, /x/, () => {}]
+    expect(vtils.shuffle(arr2).sort()).toEqual(arr2.sort())
+  })
+})