electron-system-spellcheck

Minimal native system spellchecking addon for Electron/Node.

Originally forked from Atom's node-spellchecker; MIT attribution is preserved in LICENSE.md.

Scope

• macOS: NSSpellChecker
• Windows 10+: Windows Spell Checking API (ISpellCheckerFactory / ISpellChecker)
• Node-API via node-addon-api

Linux, Hunspell, dictionary downloads/files, DOM/editor integrations, tokenization helpers, and legacy Atom compatibility APIs are intentionally not included.

API

type SpellingError = { start: number; length: number }

class SpellChecker {
  getLanguages(): string[]
  setLanguage(language: string): boolean
  check(text: string): SpellingError[]
  getSuggestions(word: string): string[]
  addWord(word: string): void
}

const { SpellChecker } = require('@arcstudio-labs/electron-system-spellcheck')

const checker = new SpellChecker()
checker.setLanguage('en-US')
console.log(checker.check('This sentence contains an obviousmisspeling.'))
console.log(checker.getSuggestions('obviousmisspeling'))

check(text) passes the complete string to the native OS spellchecker and returns misspelled ranges as JavaScript UTF-16 code-unit { start, length } offsets. The addon does not tokenize text in JavaScript or C++.

Installation

Published packages include prebuilt binaries where available. If a matching prebuild is not present for your platform/architecture, installation falls back to node-gyp rebuild.

Platform notes

On macOS, NSSpellChecker is process-shared and has process-global language state. This synchronous wrapper reapplies each instance's selected language before native operations; avoid using one process-global spellchecker concurrently from multiple JS worker threads with different languages.

On Windows, each SpellChecker instance owns the active language-specific ISpellChecker and recreates it on setLanguage().