Массив MDN MAP
let new_array = arr.map(function callback( currentValue[, index[, array]]) {
// return element for new_array
}[, thisArg])
Bad Bison
let new_array = arr.map(function callback( currentValue[, index[, array]]) {
// return element for new_array
}[, thisArg])
const numbers = [1, 5, 10, 15];
const doubles = numbers.map(function(x) {
return x * 2;
});
// doubles is now [2, 10, 20, 30]
// numbers is still [1, 5, 10, 15]