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.

Not an Excel replacement

Basic workbook workflows are available, but detailed UI compatibility is outside this package's scope. Do not use it as the promised end-user spreadsheet experience for a product that requires Excel-equivalent UI/UX.

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.