Reast Engine

The Reast Engine (<reast-engine>) is a framework-agnostic library plus a web component that loads, parses, evaluates and renders interactive Rea stories in any browser. It can be embedded on any website with a single script tag — no framework required. The standalone build is roughly 57 KB gzipped with zero runtime dependencies (one, fflate, unpacks the ZIP).

Who this is for

This section is for two audiences, distinct from the Platform docs:

• Embedders — anyone dropping a story into an existing website or app: a blog post, a game's dialogue system, an internal tool. Start at Embedding.
• Self-hosters — anyone running the engine (and optionally the platform) on their own infrastructure instead of rea.st. Start at Getting Started and the API Reference.

If you're writing a story rather than embedding a player, see the platform's Story Design guide instead — this section documents the engine that renders stories, not how to author one.

What the engine does — and does not do

It runs the pipeline Loader → Parser → Runtime → Player. It deliberately touches no device, storage or network API outside the standalone build: it requests a capability by emitting an event and receives the answer as a variable, and it emits semantics rather than looks. It ships no lightbox, media chrome, persistence or auth — those belong to the host.

Concretely, the engine has no accounts, no hosting, and no editor: it does not know what a user is, does not store or serve .reast files (you point it at a URL or feed it a File/Blob), and does not provide any UI for writing or packaging stories. Those are the platform's job — see rea.st or self-host the platform alongside the engine.

Quick Start

CDN (simplest)

<script src="https://cdn.rea.st/engine/latest/reast-engine.iife.js"></script>
<reast-engine src="https://example.com/my-story.reast"></reast-engine>

ES Module

<script type="module">
  import { registerEngine } from 'https://cdn.rea.st/engine/latest/reast-engine.es.js';
  registerEngine();
</script>
<reast-engine src="./my-story.reast"></reast-engine>

npm

npm install @reast/engine

import { registerEngine } from '@reast/engine/player';
registerEngine(); // registers <reast-engine> custom element

Note: The @reast/engine/player subpath uses browser APIs (CSSStyleSheet, HTMLElement). Import it only in browser environments — not from Node.js or SSR contexts.

Sections

• Getting Started — Setup and first story
• Embedding — Framework integration (React, Vue, Angular, vanilla)
• Extending — Rea extensions (.rext) for authors, host extensions for embedders
• Theming — CSS custom properties for visual customisation
• Package Format — The .reast archive layout and manifest schema
• API Reference — Attributes, events, JavaScript API