js sort()方法改變原數組了怎麼辦

let arr = nums.sort((a, b) => a-b)
let arr1 = nums.map(item => item*item)
let target = arr1.sort((a, b) => a-b)  // arr1被修改

let arr = nums.sort((a, b) => a-b)
let arr1 = nums.map(item => item*item)
let target = arr1.slice().sort((a, b) => a-b)  // arr1不被修改