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    Function setParser

    • Teach the loader an asset type of your own, or replace the parser of an existing one.

      Once registered, an entry of that type goes in a preload list like any other: loader.preload counts it as one step of the progress bar and waits for it before LOADER_COMPLETE. That makes it the place for work that is not a download at all, such as a texture generated in code: done here it happens behind the loading screen, rather than on the first frame of the stage that needs it.

      The parser is called as parserFn(asset, onload, onerror, settings):

      • asset is the preload entry, { name, type, src, ... }. src is optional, so { name, type } is a complete entry for something generated.
      • Call onload() once the asset is ready, or onerror(error) if it failed. Exactly one of them, now or later.
      • Return 1 if it will call one of them, or 0 when there is nothing to load, in which case the loader moves on without waiting.
      • onload takes no value, and the loader keeps nothing for a type it does not know: keep the result yourself (a Map keyed by asset.name, say) and read it from there.

      Register before preloading. Registering the same type twice logs a warning, so do it once rather than in code that runs on every scene. A src is prefixed by loader.setBaseURL only when one is set for this type by name: the "*" wildcard does not cover custom types.

      Parameters

      • type: string

        asset type

      • parserFn: Function

        parser function, as described above

      Returns void

      Asset.type

      // a texture generated in code rather than loaded, baked behind the
      // loading screen and read back by name
      const skies = new Map();
      loader.setParser("sky", (asset, onload, onerror) => {
          bakeSky(asset.name) // the game's own generator, returning a Promise
              .then((canvas) => {
                  skies.set(asset.name, canvas);
                  onload();
              }, onerror);
          return 1;
      });
      await loader.preload([{ name: "nebula", type: "sky" }]);
      const backdrop = new Sprite(0, 0, { image: skies.get("nebula") });

      // a file format of your own, fetched from `src`
      const levels = new Map();
      loader.setParser("csv", (asset, onload, onerror) => {
          fetch(asset.src)
              .then((response) => {
                  // a 404 still resolves: without this the error page is parsed
                  if (!response.ok) {
                      throw new Error(`${asset.src}: HTTP ${response.status}`);
                  }
                  return response.text();
              })
              .then((text) => {
                  levels.set(asset.name, text.split("\n").map((row) => row.split(",")));
                  onload();
              })
              .catch(onerror);
          return 1;
      });
      loader.setBaseURL("csv", "data/levels/");
      await loader.preload([{ name: "level1", type: "csv", src: "level1.csv" }]);

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