WebAssembly Local Storage Support

The save/load system is designed to work seamlessly in both native desktop applications and WebAssembly environments running in a web browser.

How It Works

When your game runs in a web browser via WebAssembly, there is no traditional filesystem available. Instead, the save/load system automatically switches to using the browser's Local Storage API. This is done transparently, so your game code doesn't need to handle platform differences.

Path Handling

Path handling is abstracted to work across different platforms:

Native Desktop: Saves are stored in the saves/ directory relative to the game executable
WebAssembly: Saves are stored in the browser's local storage with keys prefixed with saves/

This is implemented using bevy-persistent's storage backend system, where paths starting with /local/ are mapped to browser local storage.

Storage Limitations

When running in WebAssembly, be aware of these limitations:

Storage Size: Browsers typically limit local storage to 5-10MB total. This means all your saves combined should stay under this limit.
Persistence: Unlike files on a desktop computer, local storage can be cleared if:
- The user clears their browser data/cache
- The browser decides to free up space
- The user is in private/incognito mode (storage will be temporary)
Serialization Format: The system uses bincode serialization for efficiency, which works well for both platforms but produces binary data. In the browser, this binary data is base64-encoded to be stored in local storage.

Debugging WebAssembly Storage

To inspect saved game data in a browser:

Open your browser's developer tools (F12 or right-click > Inspect)
Go to the "Application" tab (Chrome) or "Storage" tab (Firefox)
Look for "Local Storage" in the left panel
Select your site's domain
Look for entries with keys starting with saves/

Implementation Details

The path handling is implemented through the get_storage_path helper function, which conditionally compiles different paths based on the target platform:

#![allow(unused)]
fn main() {
fn get_storage_path(filename: &str) -> PathBuf {
    #[cfg(target_arch = "wasm32")]
    {
        // For WebAssembly, use local storage with a prefix
        Path::new("/local/saves").join(filename)
    }
    
    #[cfg(not(target_arch = "wasm32"))]
    {
        // For native platforms, use the filesystem
        Path::new("saves").join(filename)
    }
}
}