[Basic Algorithm Scripting: Mutations | freeCodeCamp.org](https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/basic-algorithm-scripting/mutations)

第一版（未能通过所有测试）：

```js function mutation(arr) { let str1 = arr[0] let arr2 = arr[1].split('') for (let i = 0; i < arr2.length; i++) { if (str1.includes(arr2[i]) == false) return false } return true }

mutation(['hello', 'hey']) ```

第二版（成功通过）

```js function mutation(arr) { let str1 = arr[0].toLowerCase() let arr2 = arr[1].split('') for (let i = 0; i < arr2.length; i++) { if (str1.includes(arr2[i].toLowerCase()) == false) return false } return true }

console.log(mutation(['Mary', 'Army'])) ```