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Version: 2022sp

Assignment 3

In this assignment we will be practicing conditional rendering and lifting state up!

Step 0 - Setup

Create a Next.js using our starter code with the following command:

yarn create next-app --typescript --example "" YOUR_DIR_NAME

Step 1 - Hit The Ground Running

As with A2, run yarn dev in the project directory to start the server and navigate to localhost:3000 to see what the starter code gives you.

Here are the important files you'll be working with:

  • React Components
    • components/game/Game.tsx
      • This is where our game state will live and be passed down from!
      • Splits the UI into two sections, each of which is its own React component
    • components/game/ClickerSection.tsx
      • Displays the number of BRBs you have, as well as other stats
      • Has a button that should give you BRBs when clicked
    • components/game/UpgradesSection.tsx
      • Displays a list of upgrades using the UpgradeDisplay component
      • Fairly simple - is just a wrapper around the upgrade list
    • components/game/UpgradeDisplay.tsx
      • Displays stats of a particular upgrade (purchased count, price, etc)
      • Has a button that should buy the upgrade when clicked
  • Other Files
    • data/index.ts
      • Where all your GAME DATA πŸ€‘ is
      • Make sure to add at least one more upgrade to your game
    • types/index.ts
      • Just has one type: Upgrade
      • No need to change in this assignment

As always, make sure to fill in all the TODOs before submitting!

Step 2 - Dealing with Lifted State

In A2, we had the whole game all in one component. But now it's in pieces 😭

Here is a UML diagram that captures how the starter code is set up:

component diagram

Game.tsx has all the lifted state, but it needs to be passed down! The starter code is not complete, which means that your first task is to pass down the props that the other components need.

Here are all the additional props that need to be passed down:

  • ClickerSection
    • brbs
    • setBRBs
  • UpgradesSection
    • setBRBs
    • upgradeCounts
    • setUpgradeCounts
  • UpgradeDisplay
    • setBRBs
    • upgradeCounts
    • setUpgradeCounts

Remember that adding a required prop is a TWO-FOLD process:

  1. In the (child) "receiving component", add it to the Props type
  2. In all (parent) "giving components", supply the prop in JSX (<Component />)

FAQ for Step 2

What is the type of "setter" functions like setBRBs and setUpgradeCounts?

Best way to check a type is by hovering over the variable in your IDE!

If you hover over setBRBs, you will see Dispatch<SetStateAction<number>>

You will find that the type for the setter function for useState<T> will be Dispatch<SetStateAction<T>> for some type T representing the state.

Should I always be passing down the state variable/setter function directly to child components?

You don't have to! We do it in most cases in this assignment for simplicity.

However, you can see that clickIncome and tickIncome is passed down to ClickerSection as props. Since those two values are just a function of upgradeCounts (covered in Step 3), you can pass down upgradeCounts as a prop instead, and do all the calculation in ClickerSection instead of Game.

However(ever), in our assignment we calculate tickIncome in Game instead of ClickerSection because the tick logic is in Game and relies on the value of tickIncome.

TL;DR - Props do not have to mirror state in parent components, you should aim to design them in most understandable/practical way!

Why do the Props types have the readonly thing?

We like to add the readonly keyword to attributes in Props types to remind ourselves that props are passed down and cannot be directly modified. If we try to do so, we will be warned by TypeScript b/c we have specified it to be readonly. This is an optional code style thing but we like it :)

Step 3 - Tracking Upgrades

In A2, we had only 1 upgrade you could buy. Now we can add as many upgrades as we want! However, how do we keep track of how many upgrades we've purchased?

If we have one upgrade, we can keep track of this using a single number. But what if we have n number of upgrades? There are many ways to solve this, such as with an array. However, we will be instead using the following for A3:

The Map class in JavaScript/TypeScript represents a mapping between a unique key and a value. See the MDN docs for more information on Map if you are unfamiliar.

In Game.tsx, we have a state variable called upgradeCounts of type Map<Upgrade, number>. This means that the key is of type Upgrade and the value is of number.

If we have an Upgrade in mind, we can check the corresponding mapped number, which represents how many times that particular upgrade has been purchased.

Accessing upgradeCounts

We need the values inside upgradeCounts for several parts of the game.

In Game, several stats rely on upgradeCounts.

clickIncome is 1 + the total times purchased across all upgrade categories. Buying any upgrade should increase clickIncome by 1.

tickIncome is the sum of your effective income for each upgrade (incomePerTick * number of times it was purchased)

In UpgradesDisplay, we want to display the number of times the upgrade has been purchased (purchasedCount)

We will also use this purchasedCount value to implement a feature in Step 4!

Hints For Accessing upgradeCounts

We can use upgradeCounts.get(upgrade) to retrieve the associated value for a given upgrade.

We can use [...upgradeCounts.values()] to get a list of values in the Map.

We can use [...upgradeCounts.entries()] to get a list of [key, value] pairs in the Map.

See MDN docs for more things you can do!

Modifying upgradeCounts

When we buy an upgrade, we want to increment the associated number in upgradeCounts by 1.

This should happen in the buyUpgrade function in UpgradeDisplay.

Hints For Modifying upgradeCounts

Remember that you can do either setUpgradeCounts(newValue) or setUpgradeCounts((oldValue) => newValue) to update your state.

To make a change to an existing Map, do the following

// This *modifies* the Map that upgradeCounts points to
// newValue points to the SAME Map as upgradeCounts
const newValue = upgradeCounts.set(key, newValue);

IMPORTANT Note that setUpgradeCounts may not behave as you expect when working with object references. If you call setUpgradeCounts(newValue) where newValue is the same reference as upgradeCounts, then this WILL NOT trigger an update/rerender!

To get around this issue, do the following

const newValue: Map<Upgrade, number> = upgradeCounts;
setUpgradeCounts(newValue); // this is BAD
// Creates a copy of the map so that React knows that newValue is different
setUpgradeCounts(new Map(newValue)); // this is GOOD

Step 4 - Finishing Touches

We're done with the biggest part of the assignment, which is dealing with upgrades! Now let's add some smaller stuff to make the game cooler :)

Here is a list of features to add:

  • In Game, we normally show <h1>BRB Clicker</h1> as the page header.
    • If we've purchased at least one of every upgrade, then do the following:
      • Replace the text with πŸ’°BRB ClickerπŸ’° instead (with h1 tags still)
      • Right under the header h1 tag, add a win message in a p tag
    • Refresh your memory on Conditional Rendering from Lecture 5 if you're stuck!
  • In ClickerSection, make the "Acquire BRB" button work!
    • Each click should increase BRBs by the value of clickIncome
    • This will be very similar to what you did in A2, using the onClick prop
  • In UpgradeDisplay, we need to increase the price of an upgrade each time we purchase it.
    • In Cookie Clicker, the price increases by 15% every purchase.
    • Let's yoink that! (Make sure to round up to the nearest integer)
  • In UpgradeDisplay, we want to disable the Buy button (make it greyed out and unclickable) if we don't have brbs to afford the next upgrade.
    • <button /> accepts a prop (like onClick) called disabled, which takes a boolean that decides whether the button is disabled or not.

Step 5 - Submission

Make sure you've completed all of the TODOs, including your name/netid in Footer.tsx and the hours worked in index.tsx

Once you are done, please zip up everything in your project folder EXCEPT the node_modules and .next folders.

Be extra careful with .next because it is a hidden folder, which will not show up in Finder/File Explorer by default. Please find out how to show hidden files/folders for your file browser of your choice.

Then submit to CMS!