Asset Preloader

Asset Preloader is a lightweight JavaScript module for efficiently preloading assets in web applications. It supports images, videos, sounds, 3D models, and other file types with features such as event-driven progress tracking, retry mechanisms, batch loading, and customizable UI options.

Features

• ✅ Singleton Pattern – Ensures a single instance is used for asset management.
• ✅ Event-Driven Architecture – Fires progress, complete, error, and assetLoaded events.
• ✅ Customizable UI – Disable the default UI and use a custom progress display.
• ✅ Retry Mechanism – Retries failed assets up to a defined limit before fallback.
• ✅ Batch Loading – Controls how many assets load simultaneously.
• ✅ Default Asset Fallbacks – Replace missing assets with predefined placeholders.
• ✅ Asset-Specific Callbacks – Respond when an individual asset is loaded.

Installation

Using NPM

npm install @motionharvest/asset-preloader

Usage

Importing the Preloader

import AssetPreloader from '@motionharvest/asset-preloader';

Initializing the Preloader

const preloader = new AssetPreloader(true, true); // Debug mode, Custom UI enabled

Setting Default Assets

preloader.setDefaults({
    png: 'assets/default.png',
    glb: 'assets/default.glb',
    mp3: 'assets/default.mp3'
});

Loading Assets

const assetsToLoad = [
    'assets/image.png',
    'assets/video.mp4',
    'assets/missing_model.glb',
    'assets/sound.mp3'
];
preloader.loadAssets(assetsToLoad, 3, 15000); // Batch size 3, timeout 15s

Listening to Events

preloader.addEventListener('progress', (event) => {
    console.log(`Progress: ${event.detail.progress.toFixed(2)}% for ${event.detail.url}`);
});

preloader.addEventListener('assetLoaded', (event) => {
    console.log(`Asset loaded: ${event.detail.url}`);
});

preloader.addEventListener('error', (event) => {
    console.warn(`Asset failed to load: ${event.detail}, using fallback if available.`);
});

preloader.addEventListener('complete', () => {
    console.log('All assets loaded successfully!');
});

Retrieving a Loaded Asset

const imageUrl = preloader.getAsset('assets/image.png');
if (imageUrl) {
    const img = document.createElement('img');
    img.src = imageUrl;
    document.body.appendChild(img);
}

API Reference

new AssetPreloader(debug = false, useCustomUI = false)

Creates a singleton instance of the preloader.

• debug (boolean) – Enables logging output.
• useCustomUI (boolean) – Disables default loading UI if true.

.setDefaults(defaults)

Sets default fallback assets per file type.

• defaults (object) – Key-value pairs of file extensions and default asset URLs.

.loadAssets(assetList, batchSize = null, timeoutDuration = 10000)

Loads an array of assets with optional batch size and timeout settings.

• assetList (array) – List of asset URLs to preload.
• batchSize (number) – How many assets to load simultaneously.
• timeoutDuration (number) – Maximum time in milliseconds before an asset is considered failed.

.getAsset(url)

Retrieves the loaded asset's blob URL.

• url (string) – The original asset URL.
• Returns: A blob URL if the asset is loaded, otherwise null.

Events

• progress – Fired on loading progress updates.

  preloader.addEventListener('progress', (event) => {
      console.log(`Progress: ${event.detail.progress.toFixed(2)}% for ${event.detail.url}`);
  });

• assetLoaded – Fired when an individual asset finishes loading.

  preloader.addEventListener('assetLoaded', (event) => {
      console.log(`Asset loaded: ${event.detail.url}`);
  });

• error – Fired when an asset fails to load.

  preloader.addEventListener('error', (event) => {
      console.warn(`Failed to load: ${event.detail}`);
  });

• complete – Fired when all assets have been loaded.

  preloader.addEventListener('complete', () => {
      console.log('All assets loaded successfully!');
  });

License

This project is licensed under the MIT License.

Contributing

Contributions are welcome! Feel free to open an issue or submit a pull request.

Author

Developed by Aaron Sherrill.

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Enjoy using Asset Preloader! 🚀