eslint-loader

What is eslint-loader?

eslint-loader is a webpack loader that integrates ESLint into the webpack build process. It allows you to lint your JavaScript code as part of the build process, ensuring that your code adheres to specified coding standards and conventions.

What are eslint-loader's main functionalities?

Linting JavaScript files

This feature allows you to lint JavaScript files using ESLint as part of the webpack build process. The configuration specifies that all `.js` files, excluding those in `node_modules`, should be processed by `eslint-loader`.

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: [
          {
            loader: 'eslint-loader',
            options: {
              // eslint options (if necessary)
            }
          }
        ]
      }
    ]
  }
};

Custom ESLint options

This feature allows you to specify custom ESLint options, such as the path to the ESLint configuration file (`configFile`) and whether to emit warnings instead of errors (`emitWarning`).

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: [
          {
            loader: 'eslint-loader',
            options: {
              configFile: 'path/to/.eslintrc',
              emitWarning: true
            }
          }
        ]
      }
    ]
  }
};

Other packages similar to eslint-loader

eslint-webpack-plugin

eslint-webpack-plugin is a modern alternative to eslint-loader. It provides similar functionality by integrating ESLint into the webpack build process but is designed to work with webpack 5 and above. It offers better performance and more features compared to eslint-loader.

stylelint-webpack-plugin

stylelint-webpack-plugin is a webpack plugin that integrates Stylelint into the webpack build process. While it focuses on linting CSS and other style files, it provides similar functionality to eslint-loader for stylesheets.

tslint-loader

tslint-loader is a webpack loader that integrates TSLint into the webpack build process. It is similar to eslint-loader but is specifically designed for linting TypeScript files.

README

eslint-loader

eslint loader for webpack

Install

$ npm install eslint-loader

Usage

In your webpack configuration

module.exports = {
  // ...
  module: {
    loaders: [
      {test: /\.js$/, loader: "eslint-loader", exclude: /node_modules/}
    ]
  }
  // ...
}

Options

You can pass directly some eslint options by adding an eslint entry in you webpack config:

module.exports = {
  eslint: {
    configFile: 'path/.eslintrc'
  }
}

reporter (default: eslint stylish reporter)

Loader accepts a function that will have one argument: an array of eslint messages (object). The function must return the output as a string. You can use official eslint reporters. Please note that every lines with the filename will be skipped from output because of the way the loader use eslint (just with a string of text, not a file - so no filename available)

module.exports = {
  entry: "...",
  module: {
    // ...
  }
  eslint: {
    // several examples !

    // default value
    reporter: require("eslint/lib/formatters/stylish"),

    // community reporter
    reporter: require("eslint-friendly-formatter"),

    // custom reporter
    reporter: function(results) {
      // `results` format is available here
      // http://eslint.org/docs/developer-guide/nodejs-api.html#executeonfiles()
      
      // you should return a string
      // DO NOT USE console.*() directly !
      return "OUTPUT"
    }
  }
}

Errors and Warning

By default the loader will auto adjust error reporting depending on eslint errors/warnings counts. You can still force this behavior by using emitError or emitWarning options:

emitError (default: false)

Loader will always returns errors if this option is set to true.

module.exports = {
  entry: "...",
  module: {
    // ...
  }
  eslint: {
    emitErrors: true
  }
}

emitWarning (default: false)

Loader will always returns warning if option is set to true.

quiet (default: false)

Loader will process and report errors only and ignore warnings if this option is set to true

module.exports = {
  entry: "...",
  module: {
    // ...
  }
  eslint: {
    quiet: true
  }
}

failOnWarning (default: false)

Loader will cause the module build to fail if there are any eslint warnings.

module.exports = {
  entry: "...",
  module: {
    // ...
  }
  eslint: {
    failOnWarning: true
  }
}

failOnError (default: false)

Loader will cause the module build to fail if there are any eslint errors.

module.exports = {
  entry: "...",
  module: {
    // ...
  }
  eslint: {
    failOnError: true
  }
}

Changelog

License