no-meta-schema-default.md

Disallow rules meta.schema properties to include defaults (eslint-plugin/no-meta-schema-default)

💼 This rule is enabled in the ✅ recommended config.

Since ESLint v9.15.0, rules' default options are supported using meta.defaultOptions. Additionally defining them using the default property in meta.schema is confusing, error-prone, and can be ambiguous for complex schemas.

Rule Details

This rule disallows the default property in rules' meta.schema.

Examples of incorrect code for this rule:

/* eslint eslint-plugin/no-meta-schema-default: error */

module.exports = {
  meta: {
    schema: [
      {
        elements: { type: 'string' },
        type: 'array',
        default: [],
      },
    ],
  },
  create() {},
};

module.exports = {
  meta: {
    schema: {
      type: 'object',
      properties: {
        foo: { type: 'string', default: 'bar' },
        baz: { type: 'number', default: 42 },
      },
    },
  },
  create() {},
};

Examples of correct code for this rule:

/* eslint eslint-plugin/no-meta-schema-default: error */

module.exports = {
  meta: {
    schema: [
      {
        elements: { type: 'string' },
        type: 'array',
      },
    ],
    defaultOptions: [[]],
  },
  create() {},
};

module.exports = {
  meta: {
    schema: {
      type: 'object',
      properties: {
        foo: { type: 'string' },
        baz: { type: 'number' },
      },
    },
    defaultOptions: [{ foo: 'bar', baz: 42 }],
  },
  create() {},
};

When Not To Use It

When using eslint-doc-generator to generate documentation for your rules, you may want to disable this rule to include the default property in the generated documentation. This is because eslint-doc-generator does not yet support meta.defaultOptions, see bmish/eslint-doc-generator#513.

Further Reading

• ESLint rule docs: Option Defaults
• RFC introducing meta.defaultOptions