eslint-plugin-json

eslint-plugin-json

Lint JSON files

Installation

You'll first need to install ESLint:

$ npm i eslint --save-dev

Next, install eslint-plugin-json:

$ npm install eslint-plugin-json --save-dev

Note: If you installed ESLint globally (using the -g flag) then you must also install eslint-plugin-json globally.

Usage

Add json to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:

{
    "plugins": [
        "json"
    ]
}

You can run ESLint on individual JSON files or you can use the --ext flag to add JSON files to the list.

eslint . --ext .json --ext .js
eslint example.json

FAQs

How does eslint-plugin-json work?

Starting from version 1.3, this plugin relies on what VSCode uses for its implementation of JSON validation. This plugin used to use JSHint, however due to the large size of this dependency, it was replaced.

Why doesn't this plugin use eslint itself or just JSON.parse?

eslint's parser is a JavaScript parser. JSON is a stricter subset and things that are valid JavaScript are not valid JSON. This is why something more specific is more appropriate.

While JSON.parse seems ideal, it is not designed to continue after the first error. So if you have a missing trailing comma in the start of the file, the rest of the file will go unlinted. A smarter parser that can self-correct after seeing errors is needed which the VSCode implementation provides by leveraging the jsonc-parser module.

Will this plugin provide more configuration?

Now that we have moved to a different implementation for our validation, a lot more things are possible. Optional support for JSON comments, trailing commas and schemas are possible.

Additionally, support for autofixing common errors is also possible.

Is eslint really the best tool to lint my JSON?

Not really. eslint plugin interface wasn't designed to lint a completely different language but its interface is flexible enough to allow it. So this plugin is certainly unusual.

Ideally, your editor would natively supports linting JSON. If it doesn't though, then might as well use this plugin. Hacky linting is better than no linting :)