Error: Unexpected top-level property "$schema"

Tell us about your environment

• ESLint Version: 6.0.1
• Node Version: 10.15.0
• npm Version: 6.4.1

What parser (default, Babel-ESLint, etc.) are you using? @typescript-eslint/parser

Please show your full configuration:

{
  "$schema": "http://json.schemastore.org/eslintrc",
  "parser": "@typescript-eslint/parser",
  "plugins": [
    "@typescript-eslint"
  ],
  "parserOptions": {
    "project": "./tsconfig.json"
  },
  "rules": {
    "@typescript-eslint/restrict-plus-operands": "error"
  }
}

What did you expect to happen?

The $schema field is the standard way to tell editors where to find schema for a JSON file. Without this field, IntelliSense won’t be available when people edit the .eslint.json config file.

The $schema field is documented in the JSON Schema spec: https://json-schema.org/latest/json-schema-core.html#rfc.section.7

What actually happened? Please include the actual, raw output from ESLint.

It appears that when ESLint validates the .eslint.json file, it rejects the $schema field. It prints this error:

Error: ESLint configuration in .eslintrc.json is invalid:
        - Unexpected top-level property "$schema".

    at validateConfigSchema (D:\GitRepos\eslint-test\node_modules\eslint\lib\shared\config-validator.js:286:15)
    at ConfigArrayFactory._normalizeConfigData (D:\GitRepos\eslint-test\node_modules\eslint\lib\cli-engine\config-array-factory.js:469:9)
    at ConfigArrayFactory._loadConfigDataInDirectory (D:\GitRepos\eslint-test\node_modules\eslint\lib\cli-engine\config-array-factory.js:445:33)
    at ConfigArrayFactory.loadInDirectory (D:\GitRepos\eslint-test\node_modules\eslint\lib\cli-engine\config-array-factory.js:401:18)
    at CascadingConfigArrayFactory._loadConfigInAncestors (D:\GitRepos\eslint-test\node_modules\eslint\lib\cli-engine\cascading-config-array-factory.js:304:46)
    at CascadingConfigArrayFactory.getConfigArrayForFile (D:\GitRepos\eslint-test\node_modules\eslint\lib\cli-engine\cascading-config-array-factory.js:249:18)
    at FileEnumerator._iterateFilesRecursive (D:\GitRepos\eslint-test\node_modules\eslint\lib\cli-engine\file-enumerator.js:408:49)
    at _iterateFilesRecursive.next (<anonymous>)
    at FileEnumerator.iterateFiles (D:\GitRepos\eslint-test\node_modules\eslint\lib\cli-engine\file-enumerator.js:254:49)
    at iterateFiles.next (<anonymous>)

Are you willing to submit a pull request to fix this bug?

Yes. The simplest fix is for ESLint to delete the $schema field after it loads the file.

If people agree that we should fix this, I’m happy to create the PR.

[platinumazure]

I don’t think we would specifically support $schema, but I wonder if we could have a whitelist of extra keys we will allow but ignore, and maybe we could add that key to such a list.

I would be okay with evaluating a proposal along those lines in a new issue.

[octogonz]

It’s a pretty cool feature! You get tab completion when typing:

…and error-underlining if you type it wrong:

…and documentation tooltips when you mouse over a setting:

The editor obtains this information by downloading the schema (e.g. http://json.schemastore.org/eslintrc) that it discovers from the $schema field.