@tabnas/json5

A Tabnas / Jsonic grammar plugin that parses JSON5 text into JavaScript values — with comments, unquoted and single-quoted keys, single-quoted strings, trailing commas, hexadecimal integers, Infinity / NaN, leading- and trailing-decimal numbers, explicit + signs, and string line continuations.

Passes the full official json5/json5-tests corpus.

Install

npm install @tabnas/parser @tabnas/jsonic @tabnas/json5

Example

const { Tabnas } = require('@tabnas/parser')
const { jsonic } = require('@tabnas/jsonic')
const { Json5 } = require('@tabnas/json5')

const j = new Tabnas().use(jsonic).use(Json5)

const src = `{
  // a JSON5 document
  name: 'Alice',
  tags: ['admin', 'user',],
}`

j.parse(src)   // => { name: 'Alice', tags: ['admin', 'user'] }

jsonic must be applied before Json5: it supplies the relaxed-JSON rules the plugin constrains and extends.

Documentation

Full documentation, following the Diátaxis framework:

• Tutorial — learn the plugin from a guided first parse.
• How-to guide — task recipes (options, errors, strictness).
• Reference — the API, every option, and accepted syntax.
• Concepts — how it builds JSON5 on the engine, and why.

Grammar diagram

The installed grammar as a railroad/syntax diagram, generated with @tabnas/railroad:

A vertical ASCII version is in doc/grammar.txt. The grammar source lives in the repository-root json5-grammar.jsonic and is embedded into this port and the Go port by embed-grammar.js.

License

Copyright (c) 2021-2026 Richard Rodger and other contributors, MIT License.