🧩 Variable Scope in Scripts

What is scope?

Scope determines where you can access a variable inside the editor’s scripts. In JavaScript—and therefore in the engine’s scripting system—variables can have different visibility levels depending on how they are declared.

📖 Ways to declare variables

✅ Example: local (private) variable

// Script A
let score = 0;

function Update(obj, dt) {
  score += dt;
  console.log(score);
}

In this case, score only exists inside this script. If another script tries to access it, it will throw an error.

🌍 Example: global variable (shared between scripts)

// Script A
var Score = 0;

// Script B
function Start(obj) {
  console.log("Current score:", Score);
  Score += 10;
}

Because var is used, the variable Score is available in any script loaded in the scene.

🎮 Example: variable stored inside an object

// Player script
function Start(obj) {
  obj.Score = 0;
}

function Update(obj, dt) {
  obj.Score += 1;
}

From another script you can read that value easily:

let player = getObjectByName("Player");
console.log(player.Score);

This method is ideal for data belonging to each object (lives, energy, inventory...).

🌐 Using window.MyVariable (Persistent Global Variable)

In JavaScript, anything stored in the window object becomes a true global variable. This means it is accessible from any script and it does not reset when you change scenes inside the engine.

This is extremely useful for data that must survive between levels, such as:

• Coins
• Unlocked items
• Player progress
• Settings

✅ Example: declaring a persistent global variable

// Declare only once
if (!window.playerCoins) window.playerCoins = 0;

// Use anywhere:
window.playerCoins += 10;
console.log(window.playerCoins);

Because the value is stored in window, it is never lost unless:

• The entire game page reloads
• You manually reset it

🎮 Example using window with buttons

function Start(obj) {
  if (!window.totalClicks) window.totalClicks = 0;

  _onClickUp(obj, () => {
    window.totalClicks++;
    console.log("Click count:", window.totalClicks);
  });
}

This counter will increase across all scenes and will remain valid until the player closes or reloads the game.

🧠 Example: global data system (GameData)

// Main script
if (!window.GameData) window.GameData = {};
GameData.Score = 0;

// Any other script:
GameData.Score += 5;
console.log(GameData.Score);

This technique allows you to have a controlled global “container” for your game values without polluting the global scope with loose variables.

🖱️ Practical example with buttons and global variables

This example shows how to combine global variables with UI events. Here we declare a global variable Score in one script and modify it from another that controls a button.

🎯 Script 1 – Score controller

// Script: ScoreController.js
var Score = 0;

function Update(obj, dt) {
  console.log("Current score:", Score);
}

🖱️ Script 2 – Shop button

// Script: ShopButton.js
function Start(obj) {
  _onClickUp(obj, () => {
    ShowInAppPurchases();
    Score += 1;
  });
}

Because the variable Score was declared with var, both scripts share the same value. Each click on the button will increase the global counter.