The template engine behind Formfeed: Jinja2, Liquid and Handlebars templates with one set of helpers, compiled and rendered to a complete HTML document. The same package runs the web editor's preview, the formfeed CLI and Formfeed's render servers, so what it produces locally is what the API renders. It works in browsers and Node 22+ and uses no Node-only APIs.

Most projects need the CLI and @formfeed/testing rather than this package. Use it to embed template compilation in your own tools, such as a custom preview.

npm install @formfeed/engine

import {
  getEngine,
  defaultHelpers,
  defaultLimits,
  assembleDocument,
} from '@formfeed/engine';

const engine = getEngine('liquid');
const compiled = engine.compile('<h1>{{ title | upper }}</h1>', {});
const analysis = engine.analyze('<h1>{{ title | upper }}</h1>');
// analysis.variables → [{ path: ['title'], ... }], analysis.diagnostics → []

const html = await engine.render(
  compiled,
  { title: 'Hello' },
  {
    locale: 'de-DE',
    timezone: 'Europe/Berlin',
    currency: 'EUR',
    partials: () => undefined,
    helpers: defaultHelpers(),
    limits: defaultLimits,
  },
);

const document = assembleDocument({
  html,
  css: '',
  head: '',
  settings: { paper: { format: 'A4' } },
  kind: 'pdf',
});

The supported surface is the Engine interface (compile, analyze, render) returned by getEngine, the defaultHelpers() registry and defaultLimits, plus assembleDocument, renderVersion and inferSchema. compile throws EngineSyntaxError with line and column.

What is inside

Module	Contents
`engines/`	`jinja2` (Nunjucks with a Python compatibility layer), `liquid` (LiquidJS), `handlebars`, each implementing `Engine`
`helpers/`	One helper registry for all three dialects: formatting (`money`, `date`, `number`, `numToWords`, `t`), text, collections, codes (`qrcode`, `barcode`, `epcQr`), document (`asset`, `pageBreak`, `image`, `chart`)
`analysis/`	Block pairing and sample-data checks behind every `analyze()`
`schema.ts`	`inferSchema(sample)` to JSON Schema 2020-12
`assemble.ts`	Template settings, print reset, `assembleDocument()` and `renderVersion()` (body, header, footer, title)
`import/`	`importApitemplate()` and `importApitemplateFromApi()`, `importPdfmonkey()` and `importJsreport()`: convert templates of apitemplate.io, PDFMonkey and jsreport into Formfeed drafts
`office/`	Word and PowerPoint templates: `renderOffice()` fills a `.docx` or `.pptx` file, `analyzeOffice()` lists its tags, variables and findings per part and paragraph, `OfficeTemplateError` carries the findings of a document that cannot be filled, and `starterDocument()` and `starterPresentation()` return example files with their sample data