PIXI.Loader

const loader = PIXI.Loader.shared; // PixiJS exposes a premade instance for you to use.
// or
const loader = new PIXI.Loader(); // You can also create your own if you want

const sprites = {};

// Chainable `add` to enqueue a resource
loader.add('bunny', 'data/bunny.png')
      .add('spaceship', 'assets/spritesheet.json');
loader.add('scoreFont', 'assets/score.fnt');

// 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).
loader.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).
loader.use(parsingMiddleware);

// The `load` method loads the queue of resources, and calls the passed in callback called once all
// resources have loaded.
loader.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.
    sprites.bunny = new PIXI.TilingSprite(resources.bunny.texture);
    sprites.spaceship = new PIXI.TilingSprite(resources.spaceship.texture);
    sprites.scoreFont = new PIXI.TilingSprite(resources.scoreFont.texture);
});

// 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.