Browser Usage

hizi engine generator works in the browser using OPFS (Origin Private File System) for file storage. The same HiziEngineGenerator class is used in both Node.js and browser — environment detection is automatic.

Requirements

• Must run in a dedicated Web Worker (required for OPFS sync access handles)
• Server must set Cross-Origin-Isolation headers for OPFS access:
  • Cross-Origin-Opener-Policy: same-origin
  • Cross-Origin-Embedder-Policy: require-corp

Import

import { HiziEngineGenerator } from '@hizi.io/engine-generator';

Generating and Downloading

All files are plain JSONL during generation — no compression needed at runtime.

const generator = new HiziEngineGenerator();

// Start — writes to OPFS
await generator.start('/sim-output');

// Record results (same as Node.js)
for (const outcome of simulationResults) {
  generator.addResult(outcome.scenario, {
    win: outcome.win,
    metaTags: outcome.tags,
  });
}

// Finalize — writes entries to OPFS, closes scenario stream
await generator.end();

// Get generated file contents
const files = generator.getOutputFiles();
// Map { 'entries.jsonl' => '...', 'scenarios.jsonl' => '...' }

Compressing for Download

To produce brotli-compressed .br files in the browser, use brotli-wasm:

npm install brotli-wasm

import brotliWasm from 'brotli-wasm';

const bw = await brotliWasm;
const compress = (data: string) =>
  bw.compress(new TextEncoder().encode(data), { quality: 9 });

const files = generator.getOutputFiles();
const entriesBr = compress(files.get('entries.jsonl')!);
const scenariosBr = compress(files.get('scenarios.jsonl')!);

Available Methods

Method / Property	Description
start(dir)	Start streaming to OPFS
addResult()	Record a game outcome (scenarios stream directly to disk)
end()	Finalize output — write entries, close scenario stream
getOutputFiles()	Get generated files as Map<string, string> (entries only)
outputDirectory	OPFS path (available after end()). Read scenarios from OPFS directly without loading into memory.