Answer 1

I don't understand your question.

The spread operator spreads the values of an array or object into an iterable 'list'.

const arr = [1, 2, 3];
const arr2 = [...arr, 4, 5];
console.log(arr2);
//1, 2, 3, 4, 5

I think you are referring to rest parameters. Rest transform the arguments provided into an array.

function rest(...args) {
console.log(args[2]);
}

rest(1, 2, 3, 4);
//Outputs 3