how to add to arr in js code example

Example 1: js add function to array

//create an new function that can be used by any array
Array.prototype.second = function() {
  return this[1];
};

var myArray = ["item1","item2","item3"];
console.log(myArray.second());//returns 'item2'

Example 2: add array to array javascript

// SPREAD OPERATOR
 const list1 = ["pepe", "luis", "rua"];
 const list2 = ["rojo", "verde", "azul"];
 const newList = [...list1, ...list2];
 // ["pepe", "luis", "rua", "rojo", "verde", "azul"]