Docs Editor Wasm Model/Schema Cases Scenarios Tips Playground Coverage

Rich text with Rust + WebAssembly

Concepts that appear when the document core lives in Rust and ships as WASM, while the browser still owns IME, selection, and much of input—plus the JS↔WASM boundary cost model.

Overview

Moving the editor “brain” to Rust does not remove browser editing quirks: composition, clipboard normalization, selection APIs, and undo interaction remain host concerns unless you replace the surface entirely (e.g. canvas with a custom input stack—then you inherit different costs).

These pages focus on architecture and boundaries: where editing happens, how IME relates to your Rust model, how data crosses the JS↔WASM line, and how collaboration layers (CRDT) often sit next to WASM modules.

For language-agnostic editor design (schema, transactions, HTML mapping), use Editor . Here we assume a Rust core + browser host.

Why a whole section?

  • Editing model choices (DOM vs canvas vs hybrid) change who implements caret, IME, and accessibility.
  • IME is not “implemented in Rust” in the browser: you integrate with composition events and reconcile to your model.
  • FFI: every keystroke or paste can accidentally copy whole documents across the boundary—design matters as much as algorithms.
  • Collaboration often uses Rust CRDT crates with WASM bindings while the visible editor remains JS-hosted.

How this fits the rest of the site

Scenarios and Cases document real browser behavior (IME, paste, selection). WASM teams hit the same phenomena; these guides explain how they connect to a Rust core.

Guides

Editing approaches

contenteditable + WASM: source of truth, event order, DOM↔model loop, normalization, and when to call Rust.

IME & composition

composition events, syncing a Rust document model, and why the browser still owns the IME.

JS ↔ WASM boundary

Strings, copies, batched ops, async vs input events, and keeping the hot path cheap.

Clipboard & input routing

beforeinput, paste, routing decisions in JS vs sanitization in WASM.

Tooling, bundle & workers

wasm-pack, wasm-opt, code splitting, Web Workers, COOP/COEP and threads.

Collaboration & CRDT (WASM)

Yrs/y-crdt, bridging to Yjs, snapshots vs update streams with an editor host.

Selection, Range & offsets

UTF-16 vs UTF-8 indices, Selection/Range in JS, mapping to a Rust model and getTargetRanges.

Undo & redo model

Browser undo stack vs model history, programmatic DOM, and WASM-hosted transactions.

Accessibility (WASM host)

Roles, focus, screen readers when the editable surface is still the browser.

Testing & debugging

E2E, profiling the JS↔WASM boundary, reproducing IME and paste in CI.

Security & deployment

CSP, SRI, module integrity, and hosting WASM next to contenteditable.