@xl3-lang/xl3

The JavaScript/TypeScript reference implementation of xl3 — an open standard for declarative Excel transformation.

xl3 lets you use an Excel workbook as a template: you write rules in cells with a small embedded expression language (XTL), and the engine renders formatted .xlsx output from your Excel data. The rules live in the spreadsheet, authored by the person who owns the report format; the engine is owned by developers.

• Standard & spec: https://xl3.io — the language is spec-first and language-neutral. This package is one conforming implementation.
• Repository: https://github.com/xl3-lang/xl3 (this package lives in impl/js/)
• Spec: spec/
• Conformance corpus: conformance/

Install

npm install @xl3-lang/xl3

Requires Node.js >= 20.12. Also runs in the browser via the prebuilt IIFE bundle (@xl3-lang/xl3/bundle, exposes window.xl3).

Usage

import { convert } from '@xl3-lang/xl3';
import { readFileSync } from 'node:fs';

const toArrayBuffer = (b: Buffer): ArrayBuffer =>
  b.buffer.slice(b.byteOffset, b.byteOffset + b.byteLength) as ArrayBuffer;

const template = toArrayBuffer(readFileSync('template.xlsx'));
const data = toArrayBuffer(readFileSync('data.xlsx'));

// Returns Array<{ filename: string; data: Uint8Array }> — one entry per
// output workbook (a template can fan out to multiple files by group key).
const outputs = await convert(template, data);

for (const { filename, data } of outputs) {
  writeFileSync(filename, data);
}

Conformance

This implementation is validated against the standard's language-neutral conformance corpus. From the repository root:

npm run conformance          # Stage 1
npm run conformance:stage2   # Stage 1 + OOXML canonicalization

License

MIT © xl3 contributors