Transforming Arrays

Sometimes you will want to apply the same operation to each item in an array, creating a new array with the changed items. You can do this using map().

Example:

function double(number) {
  return number * 2;
}
const numbers = [5, 2, 7, 6];
const doubled = numbers.map(double);
console.log(doubled); // [ 10, 4, 14, 12 ]

Filtering Arrays

Sometimes you'll w...