eslint-plugin-vue

Official ESLint plugin for Vue.js

❗ Attention - this is documentation for version 5.x ❗

This branch contains eslint-plugin-vue@next which is a pre-released 5.0, but it's not the default version that you get with npm install eslint-plugin-vue. In order to install this you need to specify either "eslint-plugin-vue": "next" in package.json or do npm install eslint-plugin-vue@next.

Please try it and report any issues that you might have encountered.

If you want to check previous releases go here.

🎨 Playground on the Web

You can try this plugin on the Web.

• https://mysticatea.github.io/vue-eslint-demo/

❕ Requirements

• ESLint ^5.0.0.
• Node.js >=6.5.0

💿 Installation

npm install --save-dev eslint eslint-plugin-vue@next

🚀 Usage

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

Example .eslintrc.js:

module.exports = {
  extends: [
    // add more generic rulesets here, such as:
    // 'eslint:recommended',
    'plugin:vue/essential'
  ],
  rules: {
    // override/add rules settings here, such as:
    // 'vue/no-unused-vars': 'error'
  }
}

Single File Components

ESLint only targets .js files by default. You must include the .vue extension using the --ext option or a glob pattern.

Examples:

eslint --ext .js,.vue src
eslint src/**/*.{js,vue}

Attention

All component-related rules are being applied to code that passes any of the following checks:

• Vue.component() expression
• Vue.extend() expression
• Vue.mixin() expression
• export default {} in .vue or .jsx file

If you however want to take advantage of our rules in any of your custom objects that are Vue components, you might need to use special comment // @vue/component that marks object in the next line as a Vue component in any file, e.g.:

// @vue/component
const CustomComponent = {
  name: 'custom-component',
  template: '<div></div>'
}

Vue.component('AsyncComponent', (resolve, reject) => {
  setTimeout(() => {
    // @vue/component
    resolve({
      name: 'async-component',
      template: '<div></div>'
    })
  }, 500)
})

eslint-disable functionality in <template>

You can use <!-- eslint-disable -->-like HTML comments in <template> of .vue files. For example:

<template>
  <!-- eslint-disable-next-line vue/max-attributes-per-line -->
  <div a="1" b="2" c="3" d="4">
  </div>
</template>

If you want to disallow eslint-disable functionality, please disable vue/comment-directive rule.

⚙️ Configs

This plugin provides four predefined configs:

• plugin:vue/base - Settings and rules to enable correct ESLint parsing
• plugin:vue/essential - Above, plus rules to prevent errors or unintended behavior
• plugin:vue/strongly-recommended - Above, plus rules to considerably improve code readability and/or dev experience
• plugin:vue/recommended - Above, plus rules to enforce subjective community defaults to ensure consistency

💡 Rules

Rules are grouped by priority to help you understand their purpose. The --fix option on the command line automatically fixes problems reported by rules which have a wrench 🔧 below.

Base Rules (Enabling Correct ESLint Parsing)

Enforce all the rules in this category, as well as all higher priority rules, with:

{
  "extends": "plugin:vue/base"
}

Priority A: Essential (Error Prevention)

Enforce all the rules in this category, as well as all higher priority rules, with:

{
  "extends": "plugin:vue/essential"
}

Priority B: Strongly Recommended (Improving Readability)

Enforce all the rules in this category, as well as all higher priority rules, with:

{
  "extends": "plugin:vue/strongly-recommended"
}

Priority C: Recommended (Minimizing Arbitrary Choices and Cognitive Overhead)

Enforce all the rules in this category, as well as all higher priority rules, with:

{
  "extends": "plugin:vue/recommended"
}

Uncategorized

Deprecated

• ⚠️ We're going to remove deprecated rules in the next major release. Please migrate to successor/new rules.
• 😇 We don't fix bugs which are in deprecated rules since we don't have enough resources.

👫 FAQ

What is the "Use the latest vue-eslint-parser" error?

The most rules of eslint-plugin-vue require vue-eslint-parser to check <template> ASTs.

Make sure you have one of the following settings in your .eslintrc:

• "extends": ["plugin:vue/recommended"]
• "extends": ["plugin:vue/base"]

If you already use other parser (e.g. "parser": "babel-eslint"), please move it into parserOptions, so it doesn't collide with the vue-eslint-parser used by this plugin's configuration:

- "parser": "babel-eslint",
  "parserOptions": {
+     "parser": "babel-eslint",
      "ecmaVersion": 2017,
      "sourceType": "module"
  }

The vue-eslint-parser uses the parser which is set by parserOptions.parser to parse scripts.

Why doesn't it work on .vue file?

1. Make sure you don't have eslint-plugin-html in your config. The eslint-plugin-html extracts the content from <script> tags, but eslint-plugin-vue requires <script> tags and <template> tags in order to distinguish template and script in single file components.

  "plugins": [
    "vue",
-   "html"
  ]

2. Make sure your tool is set to lint .vue files.

• CLI targets only .js files by default. You have to specify additional extensions by --ext option or glob patterns. E.g. eslint "src/**/*.{js,vue}" or eslint src --ext .vue.
• VSCode targets only JavaScript or HTML files by default. You have to add "vue" to the "eslint.validate" array in vscode settings. e.g. "eslint.validate": [ "javascript", "javascriptreact", "vue" ]

⚓ Semantic Versioning Policy

This plugin follows semantic versioning and ESLint's Semantic Versioning Policy.

📰 Changelog

We're using GitHub Releases.

🍻 Contribution guide

In order to add a new rule, you should:

• Create issue on GH with description of proposed rule
• Generate a new rule using the official yeoman generator
• Run npm start
• Write test scenarios & implement logic
• Describe the rule in the generated docs file
• Make sure all tests are passing
• Run npm run update in order to update readme and recommended configuration
• Create PR and link created issue in description

We're more than happy to see potential contributions, so don't hesitate. If you have any suggestions, ideas or problems feel free to add new issue, but first please make sure your question does not repeat previous ones.

Working with rules

Before you start writing new rule, please read the official ESLint guide.

Next in order to get an idea how does the AST of the code that you want to check looks like, you can use one of the following applications:

• astexplorer.net - best tool to inspect ASTs, but it doesn't support Vue templates yet
• ast.js.org - not fully featured, but supports Vue templates syntax

Since single file components in Vue are not plain JavaScript, we can't use the default parser, and we had to introduce additional one: vue-eslint-parser, that generates enhanced AST with nodes that represent specific parts of the template syntax, as well as what's inside the <script> tag.

To know more about certain nodes in produced ASTs, go here:

• ESTree docs
• vue-eslint-parser AST docs

The vue-eslint-parser provides few useful parser services, to help traverse the produced AST and access tokens of the template:

• context.parserServices.defineTemplateBodyVisitor(visitor, scriptVisitor)
• context.parserServices.getTemplateBodyTokenStore()

Check out an example rule to get a better understanding of how these work.

Please be aware that regarding what kind of code examples you'll write in tests, you'll have to accordingly setup the parser in RuleTester (you can do it on per test case basis though). See an example here

If you'll stuck, remember there are plenty of rules you can learn from already, and if you can't find the right solution - don't hesitate to reach out in issues. We're happy to help!

🔒 License

See the LICENSE file for license rights and limitations (MIT).