# User Guide

# 💿 Installation

npm install --save-dev eslint eslint-plugin-svelte svelte

# 📖 Usage

# Configuration

# New Config (eslint.config.js)

Use eslint.config.js file to configure rules. See also: https://eslint.org/docs/latest/use/configure/configuration-files-new.

Example eslint.config.js:

import eslintPluginSvelte from 'eslint-plugin-svelte';
export default [
  // add more generic rule sets here, such as:
  // js.configs.recommended,
  ...eslintPluginSvelte.configs['flat/recommended'],
  {
    rules: {
      // override/add rules settings here, such as:
      // 'svelte/rule-name': 'error'
    }
  }
];

This plugin provides configs:

• eslintPluginSvelte.configs['flat/base'] … Configuration to enable correct Svelte parsing.
• eslintPluginSvelte.configs['flat/recommended'] … Above, plus rules to prevent errors or unintended behavior.
• eslintPluginSvelte.configs['flat/prettier'] … Turns off rules that may conflict with Prettier (You still need to configure prettier to work with svelte yourself, for example by using prettier-plugin-svelte.).
• eslintPluginSvelte.configs['flat/all'] … All rules. This configuration is not recommended for production use because it changes with every minor and major version of eslint-plugin-svelte. Use it at your own risk.

See the rule list to get the rules that this plugin provides.

# Legacy Config (.eslintrc)

Use .eslintrc.* file to configure rules. See also: https://eslint.org/docs/user-guide/configuring.

Example .eslintrc.js:

module.exports = {
  extends: [
    // add more generic rule sets here, such as:
    // 'eslint:recommended',
    'plugin:svelte/recommended'
  ],
  rules: {
    // override/add rules settings here, such as:
    // 'svelte/rule-name': 'error'
  }
};

This plugin provides configs:

• plugin:svelte/base … Configuration to enable correct Svelte parsing.
• plugin:svelte/recommended … Above, plus rules to prevent errors or unintended behavior.
• plugin:svelte/prettier … Turns off rules that may conflict with Prettier (You still need to configure prettier to work with svelte yourself, for example by using prettier-plugin-svelte.).
• plugin:svelte/all … All rules. This configuration is not recommended for production use because it changes with every minor and major version of eslint-plugin-svelte. Use it at your own risk.

See the rule list to get the rules that this plugin provides.

  "plugins": [
-   "svelte3"
  ]

# Parser Configuration

If you have specified a parser, you need to configure a parser for .svelte.

For example, if you are using the "@babel/eslint-parser", configure it as follows:

module.exports = {
  // ...
  extends: ['plugin:svelte/recommended'],
  // ...
  parser: '@babel/eslint-parser',
  // Add an `overrides` section to add a parser configuration for svelte.
  overrides: [
    {
      files: ['*.svelte'],
      parser: 'svelte-eslint-parser'
    }
    // ...
  ]
  // ...
};

For example, if you are using the "@typescript-eslint/parser", and if you want to use TypeScript in <script> of .svelte, you need to add more parserOptions configuration.

module.exports = {
  // ...
  extends: ['plugin:svelte/recommended'],
  // ...
  parser: '@typescript-eslint/parser',
  parserOptions: {
    // ...
    project: 'path/to/your/tsconfig.json',
    extraFileExtensions: ['.svelte'] // This is a required setting in `@typescript-eslint/parser` v4.24.0.
  },
  overrides: [
    {
      files: ['*.svelte'],
      parser: 'svelte-eslint-parser',
      // Parse the `<script>` in `.svelte` as TypeScript by adding the following configuration.
      parserOptions: {
        parser: '@typescript-eslint/parser'
      }
    }
    // ...
  ]
  // ...
};

If you have a mix of TypeScript and JavaScript in your project, use a multiple parser configuration.

module.exports = {
  // ...
  overrides: [
    {
      files: ['*.svelte'],
      parser: 'svelte-eslint-parser',
      parserOptions: {
        parser: {
          // Specify a parser for each lang.
          ts: '@typescript-eslint/parser',
          js: 'espree',
          typescript: '@typescript-eslint/parser'
        }
      }
    }
    // ...
  ]
  // ...
};

See also https://github.com/sveltejs/svelte-eslint-parser#readme.

# Specify svelte.config.js

If you are using eslint.config.js, we recommend that you import and specify svelte.config.js. By specifying it, some rules of eslint-plugin-svelte will read it and try to behave well for you by default. Some Svelte configurations will be statically loaded from svelte.config.js even if you don’t specify it, but you need to specify it to make it work better.

Example eslint.config.js:

import eslintPluginSvelte from 'eslint-plugin-svelte';
import svelteConfig from './svelte.config.js';
export default [
  ...eslintPluginSvelte.configs['flat/recommended'],
  {
    files: [
      '**/*.svelte',
      '*.svelte'
      // Add more files if you need.
      // '**/*.svelte.ts', '*.svelte.ts', '**/*.svelte.js', '*.svelte.js',
    ],
    languageOptions: {
      parserOptions: {
        // Specify the `svelte.config.js`.
        svelteConfig
      }
    }
  }
];

# settings.svelte

You can change the behavior of this plugin with some settings.

e.g.

module.exports = {
  // ...
  settings: {
    svelte: {
      ignoreWarnings: [
        '@typescript-eslint/no-unsafe-assignment',
        '@typescript-eslint/no-unsafe-member-access'
      ],
      compileOptions: {
        postcss: {
          configFilePath: './path/to/my/postcss.config.js'
        }
      },
      kit: {
        files: {
          routes: 'src/routes'
        }
      }
    }
  }
  // ...
};

# settings.svelte.ignoreWarnings

Specifies an array of rules that ignore reports in the template.
For example, set rules on the template that cannot avoid false positives.

# settings.svelte.compileOptions

Specifies options for Svelte compile. Effects rules that use Svelte compile. The target rules are svelte/valid-compile and svelte/no-unused-svelte-ignore. Note that it has no effect on ESLint’s custom parser.

• postcss … Specifies options related to PostCSS. You can disable the PostCSS process by specifying false.
  • configFilePath … Specifies the path of the directory containing the PostCSS configuration.

# settings.svelte.kit

If you use SvelteKit with not default configuration, you need to set below configurations. The schema is subset of SvelteKit’s configuration. Therefore please check SvelteKit docs for more details.

e.g.

module.exports = {
  // ...
  settings: {
    svelte: {
      kit: {
        files: {
          routes: 'src/routes'
        }
      }
    }
  }
  // ...
};

# Running ESLint from the command line

If you want to run eslint from the command line, make sure you include the .svelte extension using the --ext option or a glob pattern, because ESLint targets only .js files by default.

Examples:

eslint --ext .js,.svelte src
eslint "src/**/*.{js,svelte}"

# 💻 Editor Integrations

# Visual Studio Code

Use the dbaeumer.vscode-eslint extension that Microsoft provides officially.

You have to configure the eslint.validate option of the extension to check .svelte files, because the extension targets only *.js or *.jsx files by default.

Example .vscode/settings.json:

{
  "eslint.validate": ["javascript", "javascriptreact", "svelte"]
}

# ❓ FAQ

# Parsing the .svelte file fails

You should check the parser configuration.

# You’re using TypeScript and the imported *.svelte component types cannot be resolved or appear to be

You can try typescript-eslint-parser-for-extra-files. Note however that it is still an experimental package.
If you know of a better solution than that please let us know.