Install

formulon-cell is the reference UI library used here for Formulon browser integration testing. It is public, but it is not a complete Excel-compatible UI: feature coverage is partial, UI/UX does not try to mirror Excel exactly, and UI bugs may remain. Install it when you want a workbook-like browser surface around the @libraz/formulon WASM engine for testing or reference.

npm install @libraz/formulon-cell zustand

zustand is a peer dependency because host applications can read the same store that the built-in chrome subscribes to.

The UI surface is intentionally reference-grade. Use your package manager lockfile for reproducibility, and upgrade intentionally when new releases land.

Quick Start

import { Spreadsheet, WorkbookHandle, presets } from '@libraz/formulon-cell'
import '@libraz/formulon-cell/styles.css'

const host = document.getElementById('sheet')!

try {
  const workbook = await WorkbookHandle.createDefault()

  const sheet = await Spreadsheet.mount(host, {
    workbook,
    features: presets.full(),
    locale: 'en'
  })

  sheet.i18n.setLocale('ja')
  sheet.setTheme('ink')
} catch (err) {
  // SharedArrayBuffer missing (no COOP/COEP), or WASM failed to init.
  showConfigurationError(err)
}

Runtime Requirement

The Formulon WASM package uses pthreads. Browsers require a cross-origin-isolated page before SharedArrayBuffer is available:

Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp

Without those headers, WorkbookHandle.createDefault() rejects by default — it does not fall back to a degraded engine silently. Catch the rejection (or pass MountOptions.onError to Spreadsheet.mount()) and show the host a configuration error instead of a spreadsheet that looks fine but never recalculates.

For tests and explicit demos only, opt in to the in-memory stub engine with preferStub: true:

const wb = await WorkbookHandle.createDefault({ preferStub: true })
wb.isStub // true — the stub only evaluates a tiny formula subset (SUM,
          // AVERAGE, IF, …; everything else returns #ERR!) and cannot
          // load or save .xlsx/.xlsb bytes at all

See Stub engine for the full decision flow and Bundler setup for hosting the required headers.