MainHub	Lessons	Game Overview
Let’s Go!	Let’s Go!	Let’s Go!

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⏳ Asynchronous I/O

Using async/await or Promises for API calls

What Is Asynchronous I/O?

Asynchronous I/O allows your game to perform tasks (like API calls, loading files, or waiting for data) without freezing the game loop.
Instead of stopping everything until the data arrives, JavaScript continues running and handles the result later.

This is essential for:

• Leaderboards
• Saving/loading game data
• Fetching assets
• Online multiplayer
• Cloud saves

JavaScript handles async operations using:

• Promises
• async/await (a cleaner way to write Promises)

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Why Games Need Async I/O

Games often need to:

• Send scores to a server
• Load leaderboard data
• Fetch player profiles
• Download assets
• Save progress

These operations take time, so they must run asynchronously to avoid freezing gameplay.

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Promises (Basic Form)

A Promise represents a value that will be available later.

Example:

fetch("https://example.com/api/leaderboard")
    .then(response => response.json())
    .then(data => console.log(data));

This means:

• Start the request
• When it finishes, run the .then()
• When the JSON is ready, run the next .then()

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async/await (Cleaner Syntax)

async/await makes asynchronous code look like normal synchronous code.

Example:

async function loadLeaderboard() {
    const response = await fetch("https://example.com/api/leaderboard");
    const data = await response.json();
    return data;
}

What’s happening?

• await pauses only inside this function
• The rest of the game continues running
• When the data arrives, the function resumes

This is the preferred modern way to write async code.

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Example: GET Request (async/await)

async function getScores() {
    const response = await fetch("https://example.com/api/scores");
    return await response.json();
}

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Example: POST Request (async/await)

async function submitScore(name, score) {
    await fetch("https://example.com/api/scores", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ name, score })
    });
}

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Integrating Async I/O Into a Game

class Game {
    constructor() {
        this.playerName = "Ironhook";
        this.score = 0;
    }

    async endGame() {
        // send score
        await submitScore(this.playerName, this.score);

        // load leaderboard
        const leaderboard = await getScores();

        console.log("Updated Leaderboard:", leaderboard);
    }
}

This demonstrates:

• Async API calls
• Using async/await inside game logic
• Non‑blocking operations
• Clean integration with gameplay

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Why?

Asynchronous I/O shows that you understand:

• How to work with async operations
• How to use Promises and async/await
• How to integrate APIs into a game
• How to avoid blocking the game loop
• How modern JavaScript handles network requests

This is a core skill for any web‑based game or application.

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JSON Parsing

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