Part 2 — 🧱 OOP (All object-oriented content)

What is OOP?

• OOP = Object-Oriented Programming.
• Object: thing with properties (data) + methods (actions).
• Class: a blueprint that defines what objects look like.

Why OOP in Cookie Clicker?

• Cookie, upgrades, shop, and player are all objects.
• OOP makes code organized, extendable, and easier to maintain.

OOP Concepts Used

• Class → e.g., Upgrade
• Object (Instance) → e.g., “Golden Cursor”
• Properties → name, cost, multiplier, owned
• Methods → canBuy(), buy()
• Encapsulation → each object manages its own data and logic

Example Student Tasks

1. Make an Upgrade class with name, cost, multiplier, owned.
2. Add canBuy() and buy() with an if statement to check cost.
3. Create at least two instances (e.g., “Metal Spoon”, “Golden Cursor”).
4. (Tie-in with Part 1) Save & load these objects with localStorage.

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Example of OOP in the Game

Here is an example of how we implemented OOP (Object-Oriented Programming) in Cookie Clicker.
The EmojiBuddy class is responsible for creating and animating emojis that bounce around the game area whenever items are purchased.

class EmojiBuddy {
  /**
   * velocity on the y axis
   * @type {number}
   */
  dy = 2;
  /**
   * velocity on the x axis
   * @type {number}
   */
  dx = 2;
  /**
   *
   * @param {string} emoji
   */
  constructor(emoji) {
    this.emojiString = emoji;
    this.animate = this.animate.bind(this);
  }
}

flowchart TD
    A[Game Start] --> B[Load Objects from localStorage]
    B -->|Exists| C[Recreate Objects from JSON]
    B -->|"No Save Found"| D[Create New Objects from Classes]

    C --> E[Objects in Memory: Upgrades, Shop, Cookie]
    D --> E

    subgraph UpgradeClass["Upgrade Class"]
        U1["Properties: name, cost, multiplier, owned"]
        U2["Method: canBuy()"]
        U3["Method: buy()"]
        U1 --> U2
        U1 --> U3
    end

    E --> F[Player Action]
    F -->|"Click Cookie"| G[Cookie Count Increases]
    F -->|"Buy Upgrade"| H{"upgrade.canBuy() ?"}   

    H -->|"No"| I[Show Message: Not Enough Cookies]
    H -->|"Yes"| J["upgrade.buy() Method Runs"]

    J --> K[Change State: cost ↑, owned ↑, power ↑]
    K --> L[Save Objects to localStorage]
    I --> L
    G --> L

    L --> E