R
Rfw

Assets

The assets package makes it easy to load images, JSON, and binary files at runtime. Loaders are asynchronous and cache results by URL, so repeated requests are instant. See the API reference for full details.

When to Use

Use these loaders when your app needs external data or media after the initial page load:

  • Images
  • Configuration JSON
  • Binary formats such as glTF

Loaders integrate with the http package and return http.ErrPending while the request is in progress. This makes them suitable for components that display loading states.

How It Works

  1. Import the package: import "github.com/rfwlab/rfw/v2/assets"
  2. Call assets.LoadImage, assets.LoadJSON, or assets.LoadModel with a URL
  3. Handle http.ErrPending to show a loading state
  4. Subsequent calls with the same URL return instantly from cache

LoadJSON internally uses http.FetchJSON to fetch and decode.

Example: Load an Image

var img js.Value
if v, err := assets.LoadImage("/static/logo.png"); err != nil {
    if errors.Is(err, http.ErrPending) {
        return core.Text("loading...")
    }
    return core.Text("failed")
} else {
    img = v
}
return core.Img().Attr("src", img.Get("src").String())

To preload assets, call the loader in OnMount so later requests are cached and instant.

Notes

  • Only works in WebAssembly builds
  • LoadModel returns raw bytes; parsing is up to you
  • Clear caches manually with assets.ClearCache
  • Remote URLs may be blocked by CORS—prefer same-origin files