Validator for Amazon States Language with Tymly Extensions JSON.

Usage no npm install needed!

<script type="module">
  import wmfsTymlyStatelint from 'https://cdn.skypack.dev/@wmfs/tymly-statelint';



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An npm package providing a validator for Amazon States Language JSON with Tymly extensions. Usable from the command-line or as a library.

It builds on statelint, a package for validating unextended Amazon States Language JSON.

From the Command-line


npm install --global @wmfs/tymly-statelint


tymly-statelint state-machine-spec [state-machine-spec...]

There are no options. If you see no output, your state machine is fine.

As a library


npm install --save @wmfs/tymly-statelint


const tymlyStateLint = require('@wmfs/statelint')

const problems = tymlyStateLint.validate(json)
if (problems.length !== 0) {
  console.log('Oh dear!')
  problems.forEach(p => console.log(`ERROR: ${p}`)
  • json is the state machine to validate. It can be a JSON object, a filename, or a file descriptor.

tymlyStatelint.validate returns an array or error strings. If the array is empty, the state machine is fine. If not, then there's a problem! The validator is exhaustive, so it will report every problem it finds, not simply bail at the first thing. The error messages have the general form <json-path to error> <description of error>.


Bug reports and pull requests are welcome on GitHub. Please be aware of our Code of Conduct


Licensed under the terms of the MIT license. Copyright (c) 2018 West Midlands Fire Service