Exercise: Cookies and Pizza

You're planning a party for 30 people, and JavaScript is doing the sums: how many cookies and boxes, how many pizzas, which are vegetarian, and what it all costs.

Get the exercise code

Open this lesson's GitHub repository, github.com/ask-codey/exercise-cookies-and-pizza, also linked from the Exercise box beside the lesson. Click Code, then Download ZIP, and unzip it into your bootcamp folder. Or clone it with Git. Then open the folder in VS Code (File > Open Folder), and open a terminal there (Terminal > New Terminal).

The requirements are in the comment at the top of cookies.js and pizza.js.

What to do

Run the tests with:

node --test

Node.js finds every file ending in .test.js and runs it. They all fail to start with. Finish the functions, running the tests as you go:

Then plan the party with node party.js.

Hints

• Math.ceil rounds up, so a part-full box or pizza still counts. To round to cents: Math.round(total * 100) / 100.
• Defaults go in the parameter list, as in C#: function cookiesNeeded(guests, perGuest = 2).
• filter, map and find take arrow functions, just like LINQ's Where, Select and FirstOrDefault.
• sort changes the array it's called on, and one test checks that the menu keeps its order. Copy it first: [...menu] makes a new array with the same pizzas. Then sort the copy with (a, b) => a.price - b.price, and slice(0, count) takes the first count.
• reduce can add up the order; findPizza finds each name's price. throw new Error(...) throws, like C#'s throw new Exception(...).
• describeOrder: names.slice(0, -1) is every name but the last.

When you're done

Every test passes, and node party.js prints:

Cookies: 60, in 5 boxes, $38.25
Pizzas: 12 for 30 guests
Vegetarian: Margherita, Veggie, Garlic Bread
Cheapest two: Garlic Bread, Margherita
3 pizzas: Margherita, Pepperoni and Veggie, $37.00
There is no Hawaiian on the menu

Submit your exercise

The exercise is how you finish this lesson. When your work is done, put it on GitHub in a repo of your own, then submit that repo's address here.

1. On GitHub, click +, then New repository. Name it (for example exercise-cookies-and-pizza), choose Public, and click Create repository. Leave out the README: your folder already has one.

2. In a terminal in your exercise folder (Git Bash on Windows), send your work to your new repo. If you downloaded the ZIP:

   git init -b main
   git add .
   git commit -m "My solution"
   git remote add origin https://github.com/your-name/exercise-cookies-and-pizza.git
   git push -u origin main
   

   If you cloned the starter instead, point your copy at your own repo, then commit and push:

   git remote set-url origin https://github.com/your-name/exercise-cookies-and-pizza.git
   git add .
   git commit -m "My solution"
   git push -u origin main
   

3. Paste your repo's address, such as https://github.com/your-name/exercise-cookies-and-pizza, into Submit your exercise on this page. The site checks that the repo is public and holds your commits, and then the lesson is complete.

Changed something after you submitted? Push it, and submit again: your latest submission is the one that counts.

So what

Functions with defaults, arrow functions, and array methods that are LINQ by another name: that's most of the JavaScript you'll write day to day. Next, you'll point it at a web page.

Key terms

• Default Parameter
• Arrow Function
• filter()
• reduce()

Related

• Arrays
• Arrow Functions