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Loader

jsColorEngine docs: ← Project README · Bench · Performance · Roadmap · Deep dive · Examples · API: Profile · Transform

A small optional convenience class for managing a collection of Profiles — a simple registry that lets you queue profiles up by key, optionally preload them in parallel, and then look them up by key later.

Note

Loader is a thin convenience layer on top of Profile. If you only have one or two profiles, just use Profile directly — Loader doesn't do anything you can't do with await Profile.loadPromise(...).

Tip

The most authoritative reference for Loader is the in-source JSDoc in src/Loader.js.

Methods

loader.add(url, key, preload)

Register a profile with the loader.

  • url — anything Profile.load() accepts (file path with 'file:' prefix, URL, base64 with 'data:' prefix, virtual name with '*' prefix, or a raw Uint8Array).
  • key — the unique ID you'll use to retrieve this profile later via loader.get(key).
  • preload — when true, the profile is loaded as part of the next loadAll() call. When false, it's loaded lazily on the first get(key) call.

await loader.loadAll()

Load every profile registered with preload: true (in parallel). Resolves once they've all finished. Profiles registered with preload: false are not touched here — they remain lazy.

await loader.get(key)

Return the Profile registered under key. If the profile is already loaded, returns immediately. Otherwise loads it on demand and caches the result.

Always check profile.loaded afterwards — a load can fail (network error, bad file, unknown virtual name) and get() will still return the Profile instance with loaded === false and lastError set.

loader.findByKey(key)

Synchronously look up a profile by key. Returns the Profile or false if not found. Does not trigger a load — use get() for that.

loader.findByURL(url)

Synchronously look up by the original URL passed to add(). Returns the Profile or false.

Usage

const { Loader, Transform, eIntent, color } = require('jscolorengine');

(async () => {
    const loader = new Loader();

    loader.add('*lab',                              'Lab',  true);   // preloaded
    loader.add('file:./profiles/sRGB_v4.icc',       'sRGB', true);   // preloaded
    loader.add('file:./profiles/GRACoL2006.icc',    'CMYK', false);  // lazy

    await loader.loadAll();   // 'Lab' and 'sRGB' are now ready

    const labProfile  = await loader.get('Lab');
    const cmykProfile = await loader.get('CMYK');   // loaded on demand here

    if (labProfile.loaded && cmykProfile.loaded) {
        const t = new Transform();
        t.create(labProfile, cmykProfile, eIntent.perceptual);

        const lab  = color.Lab(80.1, -22.3, 35.1);
        const cmyk = t.transform(lab);

        console.log(`CMYK: ${cmyk.C}, ${cmyk.M}, ${cmyk.Y}, ${cmyk.K}`);
    }
})();