Homework Assignment

This assignment covers the first week of the Intermediate Bootcamp. This repository contains 3 test files, each covering a single task. The order of the tasks does not matter. You can complete them in any order. Try to complete as many of them as you can.

First run npm install to install the dependencies. Run the tests with the command npm test. Read the instructions in this document to know what is expected of you. The tests are meant to help and guide you. Passing tests do NOT automatically mean a successful implementation. Again, tests do not equal score! You can read the tests to see exactly what it's expecting, especially if you're getting errors. However, do not change the tests.

Make sure to hand in the project the way you received it! The tests should still work and be runnable with the npm test command after you hand in your homework.

You can also run the tests for each assignment individually by executing npm test1, npm test2 and npm test3.

If you want to play around with your code yourself (not using the provided tests), here's a tip. Instead of adding test code to your solution files, create a new .js file and run it with node.

Note: we'll use the results of this homework assignment for a formal evaluation and as such you should write the code individually. Plagiarism is a violation of the Academy contract and is not in your best interest. Do not discuss the contents of the assignment with your fellow students.

How to submit your results

Send your homework to [email protected] before Saturday 22:00

Clean up your code:

• Fix the formatting/indentation
• Remove unnecessary code.

The app should be runnable simply by cloning the repository, installing dependencies, and running npm test.

Instructions

Assignment 1: ShoppingCart

1. You must create a module named ShoppingCart. The module must export a class! In other words your module.exports is not an object, a string, or anything else, but only a class.
2. Given a brand new instance of the class in a variable cart, calling cart.getItems() should return an empty array.
3. The class should have a method cart.addItem(itemName, quantity, price), which adds a new item to an internal array.
4. After adding items, a call to cart.getItems() should return an array that includes the added items.
5. Items in the array should be in this format:

   {
     name: "Name of the item",
     quantity: 1,
     pricePerUnit: 99.99
   }

6. Calling cart.clear() should remove all items from the items array. Meaning, the next call to getItems() should return an empty array.
7. Calling cart.total() should return the total value of the shopping cart. Meaning, the sum of the cost of each cart item. The cost of each item is its pricePerUnit multiplied by the quantity. Use reduce!

Assignment 2: transform

1. You must create a module named transform that exports a function named groupAdultsByAgeRange. The test imports it like this:

   const groupAdultsByAgeRange = require("./transform").groupAdultsByAgeRange

   Note: This is a named export
2. The exported groupAdultsByAgeRange should be a function.
3. The function will be called with an array of objects as its argument. The objects represent people, with a property name and a property age. Your function should group each person over the age of 18 into age ranges. Here are a few examples:

   // Example 1
   groupAdultsByAgeRange([{name: "Henry", age: 9}, {name: "John", age: 20}])
   // Should result in:
   const result = { '20 and younger': [ { name: 'John', age: 20 } ] }
   
   // Example 2
   groupAdultsByAgeRange([{name: "Anna", age: 31}, {name: "John", age: 32}, {name: "Hank", age: 60}])
   // Should result in:
   const result2 = { 
     '31-40': [ { name: 'Anna', age: 31 }, { name: 'John', age: 32 } ],
     '51 and older': [ { name: 'Hank', age: 60 } ] 
   }

4. Notice that the groups are only added to the resulting object if they are not empty. Make sure your function does the same.
5. You should use a combination of filter and reduce. If your solution uses for-loops instead of reduce for creating the final object, you will receive partial points. The use of for-loops is allowed, but try to construct the returned "grouping" object using reduce.
6. These are the groups that your code needs to return. Use the text as the name of the property:
   • 20 and younger
   • 21-30
   • 31-40
   • 41-50
   • 51 and older

Assignment 3: Asynchronous code

Note that this assignment asks you to delay the execution of functions, but the Mocha test runner sets a total limit of 2 seconds per test. So, make sure you only delay your functions for a few milliseconds.

1. You must create a module named async-functions. The test imports it with

   const {
     giveItBackLater,
     addSomePromises,
     promiseToGiveItBackLater
   } = require("./async-functions")

   Note: There should be 3 named exports that should all be functions

2. The function giveItBackLater will be called with two parameters:

   giveItBackLater(value, callback)

   The callback function should be called and given the value as a parameter. It should NOT do this right away, but later (asynchronously) using setTimeout.

3. The function promiseToGiveItBackLater(value) should return a promise that will resolve with the value later. It should use giveItBackLater. Meaning, you will wrap your callback-style function giveItBackLater with a promise-style version.

4. Calling addSomePromises(somePromise) should chain one or more promises to the somePromise and return the last one. Your code should add both a fulfillment handler and a rejection handler.

   • When somePromise resolves with a string, for example "foo", then the returned promise should resolve with a string "foofoo".
   • When somePromise is rejected with a string, for example "bar", then the returned promise should resolve with "barbarbar".

   So, your fulfillment handler should double the string and the rejection handler should triple the string. The testing code will reject or resolve the provided somePromise with a string value, and inspect what your returned promise resolves with.