immutable array

//cara 1
let array1 = [1,2,3];
let array2 = [].concat(array1);
console.log(array2); //[ 1, 2, 3 ]
array2.push(4,5,6);
console.log(array2); //[ 1, 2, 3, 4, 5, 6 ]
console.log(array1); //[ 1, 2, 3]

//cara 2
let array3 = [1,2,3];
let array4 = [...array3];
console.log(array4); //[ 1, 2, 3 ]
array4.push(4,5,6);
console.log(array4); //[ 1, 2, 3, 4, 5, 6 ]
console.log(array3); //[ 1, 2, 3