Skip to content

Latest commit

 

History

History
123 lines (81 loc) · 5.93 KB

README.md

File metadata and controls

123 lines (81 loc) · 5.93 KB
Raw
  • Start Date: 2019-05-12
  • RFC PR: #20
  • Authors: Toru Nagashima (@mysticatea)

Configuring Additional Lint Targets with .eslintrc

Summary

This proposal adds the ability to specify additional target files into configuration files. This enhancement will solve the pain that people have to use the --ext option with wanted file extensions even if they use plugins which support additional file types.

Motivation

People have to use the --ext option or glob patterns to check wanted files even if they use plugins which support additional file types.

plugins:
  - markdown
  - html
  - "@typescript-eslint"
  - react
  - vue
# ESLint checks only `*.js`.
eslint src docs

# Needs `--ext` option
eslint src docs --ext .js,.md,.html,.ts,.jsx,.tsx,.vue

However, using plugins which support additional file types is the intention that wants to check those files. The requirement of redundant CLI options is not reasonable.

Per "Related Discussions" section, this is very regularly requested; I want to configure additional target files with .eslintrc.

Detailed Design

This proposal enhances overrides property of the config file.

  • If a config file in a directory has overrides property, ESLint checks the files which are matched by any of override entries (i.e., files/excludedFiles criteria) additionally in the directory.
    • If any of files value of an override entry ended with *, this enhancement doesn't use the entry in order to avoid checking too many kinds of files.
  • This enhancement affects only the case where a directory path is provided on the CLI. If people provide glob patterns on the CLI, ESLint behaves the same as currently.
  • The --ext option precedences this enhancement. If the --ext option was given, this enhancement is disabled. So people can use the current behavior by --ext .js.
  • The ignoring configuration (.eslintignore) precedences this enhancement. If .eslintignore contains the additional target files, ESLint just ignores those as same as currently.

The overrides property means that people intend to check those files. So this behavior is intuitive.

💡 Example: 
overrides:
  - files: "*.ts"
    parser: "@typescript-eslint/parser"
  - files: "tests/**/*"
    env: { mocha: true }

With the above config, eslint . command will check *.ts files additionally. But the command doesn't check all files inside tests directory.

Code blocks

If a code block that processors extracted has the virtual filename, ESLint filters the file extension of the virtual filename with --ext option. This enhancement affects to that check. ESLint lints the code block if the overrides matches the virtual filename.

Legacy file extension processors

This enhancement doesn't affect legacy file extension processors. This means that plugins property in config files never changes the kinds of target files.

On the other hand, extends property in config files can change the kinds of target files by the overrides property in the shareable configs.

Implementation

Documentation

This enhancement needs migration guide because of a breaking change.

  • If your config contains overrides property, eslint command with directory paths lints the files which are matched automatically. This may increase errors of your command.
    If you don't want to add file types to check, please use glob patterns instead of directory paths or --ext .js option.

This enhancement, so it needs to update some documents.

  • In the description of --ext CLI option, it should say that your config file may add file types automatically.
  • In the description of overrides property, it should say that the overrides[].files property adds target files automatically.

Drawbacks

  • This is a breaking change.
  • Implicit behavior may be confusing people.

Backwards Compatibility Analysis

In the following situation, eslint command increases errors.

  • Their configuration has overrides property (with files property which doesn't end with *).
  • Their eslint command is using directory paths without --ext option.

I guess that the impact is limited because people use --ext option or glob patterns if they use configuration which affects files other than *.js.

Alternatives

  • To add extensions property that behaves as same as --ext option. Explicit reduces confusion. However, plugins and shareable configs cannot add the extensions property without the breaking change that drops old ESLint support.

Open Questions

Frequently Asked Questions

Related Discussions