# vue-eslint-parser
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The ESLint custom parser for `.vue` files.
## โคด๏ธ Motivation
This parser allows us to lint the `<template>` of `.vue` files. We can make mistakes easily on `<template>` if we use complex directives and expressions in the template. This parser and the rules of [eslint-plugin-vue](https://github.com/vuejs/eslint-plugin-vue) would catch some of the mistakes.
## ๐ฟ Installation
```bash
npm install --save-dev eslint vue-eslint-parser
```
## ๐ Usage
Write `parser` option into your `eslint.config.*` file.
```js
import vueParser from "vue-eslint-parser"
export default [
js.configs.recommended,
{
files: ["*.vue", "**/*.vue"],
languageOptions: {
parser: vueParser,
},
}
]
```
## ๐ง Options
`parserOptions` has the same properties as what [espree](https://github.com/eslint/espree#usage), the default parser of ESLint, is supporting.
For example:
```js
import vueParser from "vue-eslint-parser"
export default [
{
files: ["*.vue", "**/*.vue"],
languageOptions: {
parser: vueParser,
sourceType: "module",
ecmaVersion: "latest",
parserOptions: {
ecmaFeatures: {
globalReturn: false,
impliedStrict: false,
jsx: false
}
}
},
}
]
```
### parserOptions.parser
You can use `parserOptions.parser` property to specify a custom parser to parse `<script>` tags.
Other properties than parser would be given to the specified parser.
For example:
```js
import vueParser from "vue-eslint-parser"
import babelParser from "@babel/eslint-parser"
export default [
{
files: ["*.vue", "**/*.vue"],
languageOptions: {
parser: vueParser,
parserOptions: {
parser: babelParser,
}
},
}
]
```
```js
import vueParser from "vue-eslint-parser"
import tsParser from "@typescript-eslint/parser"
export default [
{
files: ["*.vue", "**/*.vue"],
languageOptions: {
parser: vueParser,
parserOptions: {
parser: tsParser,
}
},
}
]
```
You can also specify an object and change the parser separately for `<script lang="...">`.
```js
import vueParser from "vue-eslint-parser"
import tsParser from "@typescript-eslint/parser"
export default [
{
files: ["*.vue", "**/*.vue"],
languageOptions: {
parser: vueParser,
parserOptions: {
"parser": {
// Script parser for `<script>`
"js": "espree",
// Script parser for `<script lang="ts">`
"ts": tsParser,
// Script parser for vue directives (e.g. `v-if=` or `:attribute=`)
// and vue interpolations (e.g. `{{variable}}`).
// If not specified, the parser determined by `<script lang ="...">` is used.
"<template>": "espree",
}
}
},
}
]
```
If the `parserOptions.parser` is `false`, the `vue-eslint-parser` skips parsing `<script>` tags completely.
This is useful for people who use the language ESLint community doesn't provide custom parser implementation.
### parserOptions.vueFeatures
You can use `parserOptions.vueFeatures` property to specify how to parse related to Vue features.
For example:
```js
import vueParser from "vue-eslint-parser"
export default [
{
files: ["*.vue", "**/*.vue"],
languageOptions: {
parser: vueParser,
parserOptions: {
vueFeatures: {
filter: true,
interpolationAsNonHTML: true,
styleCSSVariableInjection: true,
customMacros: []
}
}
},
}
]
```
### parserOptions.vueFeatures.filter
You can use `parserOptions.vueFeatures.filter` property to specify whether to parse the Vue2 filter. If you specify `false`, the parser does not parse `|` as a filter.
For example:
```json
{
"parserOptions": {
"vueFeatures": {
"filter": false
}
}
}
```
If you specify `false`, it can be parsed in the same way as Vue 3.
The following template parses as a bitwise operation.
```vue
<template>
<div>{{ a | b }}</div>
</template>
```
However, the following template that are valid in Vue 2 cannot be parsed.
```vue
<template>
<div>{{ a | valid:filter }}</div>
</template>
```
### parserOptions.vueFeatures.interpolationAsNonHTML
You can use `parserOptions.vueFeatures.interpolationAsNonHTML` property to specify whether to parse the interpolation as HTML. If you specify `true`, the parser handles the interpolation as non-HTML (However, you can use HTML escaping in the interpolation). Default is `true`.
For example:
```json
{
"parserOptions": {
"vueFeatures": {
"interpolationAsNonHTML": true
}
}
}
```
If you specify `true`, it can be parsed in the same way as Vue 3.
The following template can be parsed well.
```vue
<template>
<div>{{a<b}}</div>
</template>
```
But, it cannot be parsed with Vue 2.
### parserOptions.vueFeatures.styleCSSVariableInjection
If set to `true`, to parse expressions in `v-bind` CSS functions inside `<style>` tags. `v-bind()` is parsed into the `VExpressionContainer` AST node and held in the `VElement` of `<style>`. Default is `true`.
See also to [here](https://github.com/vuejs/rfcs/blob/master/active-rfcs/0043-sfc-style-variables.md).
### parserOptions.vueFeatures.customMacros
Specifies an array of names of custom macros other than Vue standard macros.
For example, if you have a custom macro `defineFoo()` and you want it processed by the parser, specify `["defineFoo"]`.
Note that this option only works in `<script setup>`.
### parserOptions.templateTokenizer
**This is an experimental feature. It may be changed or deleted without notice in the minor version.**
You can use `parserOptions.templateTokenizer` property to specify custom tokenizers to parse `<template lang="...">` tags.
For example to enable parsing of pug templates:
```jsonc
{
"parserOptions": {
"templateTokenizer": {
// template tokenizer for `<template lang="pug">`
"pug": "vue-eslint-parser-template-tokenizer-pug",
}
}
}
```
This option is only intended for plugin developers. **Be careful** when using this option directly, as it may change behaviour of rules you might have enabled.
If you just want **pug** support, use [eslint-plugin-vue-pug](https://github.com/rashfael/eslint-plugin-vue-pug) instead, which uses this option internally.
See [implementing-custom-template-tokenizers.md](./docs/implementing-custom-template-tokenizers.md) for information on creating your own template tokenizer.
## ๐ Usage for custom rules / plugins
- This parser provides `parserServices` to traverse `<template>`.
- `defineTemplateBodyVisitor(templateVisitor, scriptVisitor, options)` ... returns ESLint visitor to traverse `<template>`.
- `getTemplateBodyTokenStore()` ... returns ESLint `TokenStore` to get the tokens of `<template>`.
- `getDocumentFragment()` ... returns the root `VDocumentFragment`.
- `defineCustomBlocksVisitor(context, customParser, rule, scriptVisitor)` ... returns ESLint visitor that parses and traverses the contents of the custom block.
- `defineDocumentVisitor(documentVisitor, options)` ... returns ESLint visitor to traverses the document.
- [ast.md](./docs/ast.md) is `<template>` AST specification.
- [mustache-interpolation-spacing.js](https://github.com/vuejs/eslint-plugin-vue/blob/b434ff99d37f35570fa351681e43ba2cf5746db3/lib/rules/mustache-interpolation-spacing.js) is an example.
- Check your version of ESLint as the location of `defineTemplateBodyVisitor` was moved from `context` to `context.sourceCode` after major version `9.x`
### `defineTemplateBodyVisitor(templateBodyVisitor, scriptVisitor, options)`
*Arguments*
- `templateBodyVisitor` ... Event handlers for `<template>`.
- `scriptVisitor` ... Event handlers for `<script>` or scripts. (optional)
- `options` ... Options. (optional)
- `templateBodyTriggerSelector` ... Script AST node selector that triggers the templateBodyVisitor. Default is `"Program:exit"`. (optional)
```ts
import { AST } from "vue-eslint-parser"
export function create(context) {
return context.sourceCode.parserServices.defineTemplateBodyVisitor(
// Event handlers for <template>.
{
VElement(node: AST.VElement): void {
//...
}
},
// Event handlers for <script> or scripts. (optional)
{
Program(node: AST.ESLintProgram): void {
//...
}
},
// Options. (optional)
{
templateBodyTriggerSelector: "Program:exit"
}
)
}
```
## โ ๏ธ Known Limitations
Some rules make warnings due to the outside of `<script>` tags.
Please disable those rules for `.vue` files as necessary.
- [eol-last](http://eslint.org/docs/rules/eol-last)
- [linebreak-style](http://eslint.org/docs/rules/linebreak-style)
- [max-len](http://eslint.org/docs/rules/max-len)
- [max-lines](http://eslint.org/docs/rules/max-lines)
- [no-trailing-spaces](http://eslint.org/docs/rules/no-trailing-spaces)
- [unicode-bom](http://eslint.org/docs/rules/unicode-bom)
- Other rules which are using the source code text instead of AST might be confused as well.
## ๐ฐ Changelog
- [GitHub Releases](https://github.com/vuejs/vue-eslint-parser/releases)
## ๐ป Contributing
Welcome contributing!
Please use GitHub's Issues/PRs.
If you want to write code, please execute `npm install` after you cloned this repository.
The `npm install` command installs dependencies.
### Development Tools
- `npm test` runs tests and measures coverage.
- `npm run build` compiles TypeScript source code to `index.js`, `index.js.map`, and `index.d.ts`.
- `npm run coverage` shows the coverage result of `npm test` command with the default browser.
- `npm run clean` removes the temporary files which are created by `npm test` and `npm run build`.
- `npm run lint` runs ESLint.
- `npm run update-fixtures` updates files in `test/fixtures/ast` directory based on `test/fixtures/ast/*/source.vue` files.
- `npm run watch` runs `build`, `update-fixtures`, and tests with `--watch` option.