Spread [es6]

let numbers = [1,2,3,4,5];
console.log(...numbers);
// 1 2 3 4 5

Rest [es6]

function sum(...num){
    if(typeof num === 'number')
      return num;
    return num.reduce( (x,y) => x+y)
}
console.log(sum([1,2,3,4,5]));
// [1, 2, 3, 4, 5]
console.log(sum(2));
// 2