// ctor
const loader = new Loader();

loader
    // Chainable `add` to enqueue a resource
    .add(name, url, options)

    // Chainable `pre` to add a middleware that runs for each resource, *before* loading that resource.
    // This is useful to implement custom caching modules (using filesystem, indexeddb, memory, etc).
    .pre(cachingMiddleware)

    // Chainable `use` to add a middleware that runs for each resource, *after* loading that resource.
    // This is useful to implement custom parsing modules (like spritesheet parsers, spine parser, etc).
    .use(parsingMiddleware)

    // The `load` method loads the queue of resources, and calls the passed in callback called once all
    // resources have loaded.
    .load((loader, resources) => {
        // resources is an object where the key is the name of the resource loaded and the value is the resource object.
        // They have a couple default properties:
        // - `url`: The URL that the resource was loaded from
        // - `error`: The error that happened when trying to load (if any)
        // - `data`: The raw data that was loaded
        // also may contain other properties based on the middleware that runs.
    });

// throughout the process multiple signals can be dispatched.
loader.onProgress.add(() => {}); // called once per loaded/errored file
loader.onError.add(() => {}); // called once per errored file
loader.onLoad.add(() => {}); // called once per loaded file
loader.onComplete.add(() => {}); // called once when the queued resources all load.

npm i && npm run build