Popcorn Hack

Define the purpose of the files in the RPG games. Using the Anatomy section, describe the RPG Game files in your own words:

  • rpg.md: Defines … and starts …
  • GameControl.js: Manages …
  • GameEnv.js: Defines …
  • Background.js: Handles …
  • Player.js: Handles …

Data Definition

This article will go through the steps of defining JSON Object data. Understanding objects is crucial for understanding JavaScript, and they are used extensively in all the code we will be looking at.

JSON Object data is used to define the sprites and backgrounds that are used within the RPG game.

Key-Value Definition

A JSON Object is a very common “Data Structure” used to represent data.

A JSON Object is a formation of key-valure pair.

As a popcord hack replace the code in two cells with “your name” and other vitals as the values in the key-value pairs.

%%js

const name = {name: 'John Doe'}
console.log(name.name)

element.append(name.name)


%%js

const person = {
    firstName: "John",
    lastName: "Doe",
    age: 30,
    fullName: function() {
        return this.firstName + " " + this.lastName;
    }
};

// Display data from the object to the console
console.log(person.firstName)
console.log(person.lastName)
console.log(person.fullName());
// Display data from the object to jupyter notebook 
element.append(person.fullName());

Image Data for Background

Shown is key JSON Object definitions for a background called water.png.

JavaScript objects are often nested

%%js

// Background data from navigation/rpg.md
const image_src = "/IanM_2025/images/rpg/water.png";
const image_data = {
    pixels: {height: 580, width: 1038}
};
const image = {src: image_src, data: image_data};

// review console to see JSON in memoory
console.log(image)

// display JSON in HTML
const image_json = JSON.stringify(image, null, 2);
element.append(`<pre>${image_json}</pre>`);

Sprite Data for Player

A sprite is the foundation of an animated player. There are many JSON Object ddefinition required to implement animations.

JavaScript Object data can be extracted with dot notation.

%%js

// Sprite data
const sprite_src = "/IanM_2025/images/rpg/turtle.png";
const sprite_data = {
    SCALE_FACTOR: 10,
    STEP_FACTOR: 1000,
    ANIMATION_RATE: 50,
    pixels: {height: 280, width: 256},
    orientation: {rows: 4, columns: 3 },
    down: {row: 0, start: 0, columns: 3 },
    left: {row: 1, start: 0, columns: 3 },
    right: {row: 2, start: 0, columns: 3 },
    up: {row: 3, start: 0, columns: 3 },
};
const sprite = {src: sprite_src, data: sprite_data};

// review console to see JSON in memoory
console.log(sprite)
console.log("----Extract Data with Dot Notation---");
console.log(sprite.data.up)

// display JSON in HTML
const sprite_json = JSON.stringify(sprite, null, 2);
element.append(`<pre>${sprite_json}</pre>`);
element.append("----Extract Data with Dot Notation---");
const sprite_partial = JSON.stringify(sprite.data.up, null, 2);
element.append(`<pre>${sprite_partial}</pre>`);