const arr = [1,2,3,4,5];

// map applies a function to each element, and returns a new array
const mappedArray = arr.map(element => element + 1); // returns a new array: [2,3,4,5,6]

// filter returns a new array consisting of elements which pass the test function
// in this, filter out the odd numbers
const filteredArray = mappedArray.filter(element => element % 2 === 0); // returns a new array: [2,4,6]

// go ahead and log them to the screen!
// forEach loops through an array, and calls the function once for every element in the array
filteredArray.forEach(element => console.log(element));
// prints: 2, 4, 6

// but arrays are composable, so you can also do:
arr.map(element => element + 1)
   .filter(element => element % 2 === 0)
   .forEach(element => console.log(element))