Labs.prefetch ​

Contract 2.0.0 · package sha256 a857eca95b35921109faf997094bb4192f12527d9d0fcd4be7e97f06425bad6e · generated from configurator-runtime.d.ts by services/onsite-scripter/scripts/build-contract-docs.mjs; edit the source, not this file.

Method of Labs · labs · since 2.0.0 · called as session.labs.prefetch

prefetch(nodes: readonly (string | DeepReadonly<ConfiguratorNode>)[], options?: SceneModelOptions): Promise<void>;

Fetches into the browser cache what a write naming these nodes would load on this device and quality tier: a ModelNode with its active descendants; a MaterialNode's maps, using the optimized twin where the runtime would. A string names a node of the current scene model; a node object is one you are about to write (it need not be in the scene model yet), and its URLs resolve as the setSceneModel that adds it would (assetBaseUrl as in SceneModelOptions). Adds nothing to the scene and records nothing; skips assets already loaded. Resolves when the files are cached; rejects AbortError on signal. For a shopper's intent (hover, focus, touch) before a pick. Precedents: HTML <link rel=prefetch>, PlayCanvas AssetRegistry.load of an asset not yet in the scene. Its requests go through the automatic preload's scheduler (spec section 5.15): low priority, at most 2 speculative requests in flight per session for both together, none started before the first complete frame or while a required model or a picked material's maps load (a started one finishes). With no scene model yet and none being written, the first frame after boot is the first complete frame, so a prefetch awaited before the first setSceneModel settles. The sibling choice and its 8-asset cap don't limit the named nodes. A write that needs a file still queued or downloading takes it over as required work, with no second download. Aborting drops only this call's interest in its queued files. A failed file (a network error or a non-success HTTP status) rejects HoloAssetError naming the first file that failed, once the call's other files settle; it never resolves as cached. The error's problem is the only record (no info().problems entry, no 'problem' event, and the failure window of spec section 6.4 doesn't start), files already cached stay cached, and a later prefetch or write fetches the failed file again.

Default: options.signal undefined; options.assetBaseUrl the runtime's asset root

Options ​

Through Session:

Through Tx:

Abort (signal) ​

This call is neither a write, a registration, a wait nor a creator (SignalOption.signal, the kinds of call).

Cancels this call; the member's JSDoc says what an abort does.

Example ​

Imports: values (has, validate, the Holo*Error classes, the pure helpers) from @holostep-configurators/runtime-client, types from @holostep-configurators/runtime-client/contract, /math and /testing names from those entries; boot from the runtime module the root's loadRuntimeAtFloor resolves to. A type your page defines is your app's: declare it there, never import it from the package.

Compiled under the contract's strict settings (examples/declaration/20-Labs.prefetch.ts):

import type { Session } from '@holostep-configurators/runtime-client/contract';
declare const session: Session;
declare const signal: AbortSignal;
declare const swatch: HTMLElement;
declare const optionId: string;
// warm an option's files on hover; forget it only when the prefetch rejects, so a file that
// failed is fetched again on the next hover
let warmed = false;
swatch.addEventListener('pointerenter', () => {
  if (warmed) return;
  warmed = true;
  session.labs.prefetch([optionId]).catch(() => (warmed = false));
});

Generic-API test (spec 3.1) ​