const primArr = [1, 2, 3];
const copyArr = [...primArr];
copyArr[0] = 99;

const objArr = [{ x: 1 }, { x: 2 }];
const copyObjArr = [...objArr];
copyObjArr[0].x = 99;

console.log(primArr[0], copyArr[0], objArr[0].x, copyObjArr[0].x);