only-one

A simple CLI tool that checks you only have one version of a dependency in your node_modules folder.

only-one react

or for multiple deps

only-one react react-dom

If none or more than one version of the deps are found the process will exit with failure. The tool works by globbing your node_modules, it has nothing to do with yarn or npm lock files and therefore checks that yarn or npm is also correctly installing into node_modules.

You may wish to add it to your test suite "test": "only-one react && mocha && eslint .".

I was motivated to build this because sometimes 3rd party libraries accidentally have react as a dependency and this can break stuff.

Please be aware if you have a large node_modules it can be quite slow because it's a lot of file paths to search through.

To install

npm install only-one --save-dev
yarn add only-one --dev

Options

--warn or -w to only warn about deps than are more than 1 and dont fail