prosemirror-rs — Node.js bindings

Node.js bindings for prosemirror, a Rust implementation of ProseMirror's document model and transform pipeline.

Installation

npm install prosemirror-rs

Design goals

• Zero unnecessary copies. The schema and document live entirely in Rust memory. Only JSON strings cross the JavaScript/Rust boundary.
• Wire-efficient. Steps arriving as JSON (e.g. from a WebSocket) can be passed directly to applyStepsJson() without any JS-level parsing.
• Database-efficient. docJson() serializes the document in Rust and returns a plain JS string, ready to write to a database with no intermediate objects.

Quick start

const { Editor } = require('prosemirror-rs');

const schemaJson = JSON.stringify({
    nodes: {
        doc:       { content: 'paragraph+' },
        paragraph: { content: 'text*', group: 'block' },
        text:      { group: 'inline' },
    },
    marks: { strong: {}, em: {} },
});

const docJson = JSON.stringify({
    type: 'doc',
    content: [{ type: 'paragraph', content: [{ type: 'text', text: 'Hello' }] }],
});

const editor = new Editor(schemaJson, docJson);
console.log(editor.version);   // 0

// Typical server loop: steps arrive as raw JSON from a WebSocket client
wss.on('message', (raw) => {
    const data = JSON.parse(raw);                     // parse envelope only
    const ok = editor.applyStepsJson(                 // steps stay as JSON string
        JSON.stringify(data.steps)
    );
    if (ok) {
        db.execute('UPDATE docs SET body = $1', [editor.docJson()]);
    }
});

Building from source

cd node
npm run build   # runs cargo build --release + copies the .node artifact
npm test        # build + run the test suite

API reference

new Editor(schemaJson, docJson)

Create an editor. Both arguments are JSON strings (schema spec and initial document). Throws Error on malformed input.

editor.applyStep(stepJson) → boolean

Apply one step supplied as a JSON string. Returns true on success, false if the step cannot be applied (document is left unchanged). Throws Error on invalid JSON.

editor.applyStepsJson(stepsJson) → boolean

Preferred method for incoming network data. Accepts a JSON array of steps as a single string — passed directly to Rust and parsed there, so nothing touches JS's JSON machinery.

The batch is atomic: if any step fails the document and version are rolled back entirely and false is returned. Throws Error on invalid JSON.

editor.applySteps(steps) → boolean

Convenience method for when steps are constructed or modified in JavaScript. Each element of steps is a JSON string for one step.

The batch is atomic: if any step fails the document and version are rolled back entirely and false is returned. Throws Error on invalid JSON.

editor.reset(docJson)

Replace the document with a new one, reusing the already-parsed schema. Resets the version counter to zero. Throws Error on malformed input.

editor.docJson() → string

Return the current document as a compact JSON string. Serialized entirely in Rust; only the final string is passed to JavaScript — suitable for direct database writes with no intermediate objects.

editor.version (number, read-only)

Number of steps successfully applied since construction or the last reset(). Use as a document version counter in collaborative-editing protocols.

Credits

The underlying Rust library was originally written by Daniel Seiler (Xiphoseer, [email protected]), who designed and implemented the document model, transform pipeline, and runtime schema system. Currently maintained by Johannes Wilm (FidusWriter, [email protected]).

ProseMirror is by Marijn Haverbeke and contributors — see prosemirror.net.

License

MIT — see LICENSE.

Copyright 2026 Johannes Wilm Copyright 2020 Daniel Seiler Copyright 2015–2026 Marijn Haverbeke and others