Practice exercise in moving away from for loops while minimizing side effects.

sideEffectMin

const waffles = [
  { name: 'Chocolate Chip', calories: 800 },
  { name: 'Blueberry', calories: 400 },
  { name: 'Whole Grain', calories: 350 },
  { name: 'Savory', calories: 600 }
];

const isHealthy = waffle => waffle.calories < 200;
const getName = waffle => waffle.name;
const getItemNames = items => items.filter(isHealthy).map(getName);

// A promise is being used just for continued practice
let verifyBreakfastOptions = new Promise(function(resolve, reject) {

  // verify the options based on the cal value above
  let healthyBreakfasts = getItemNames(waffles);

  // if an array is returned with something in it, the promise resolves, otherwise it is rejected with a message in the catch
  if (healthyBreakfasts.length) {
    resolve(healthyBreakfasts);
  } else {
    healthyBreakfasts = null;
    reject(healthyBreakfasts);
  }

});

verifyBreakfastOptions
  .then((output) => {
    // non-mutative definition that will interpret the data and convert it to a text string.
    let options = output.toString().replace(',', ' and ');
    console.log("You can eat the following:", options + '.');
  })
  .catch((output) => {
    console.log("No items were found.");
  });