@lwc/eslint-plugin-lwc

> Official ESLint rules for Lightning Web Components (LWC).

Installation

``
$ npm install eslint @babel/core @babel/eslint-parser @lwc/eslint-plugin-lwc --save-dev
`

Usage

_Starting with v3.0.0, @lwc/eslint-plugin-lwc only supports eslint@v9. Use @lwc/eslint-plugin-lwc@v1.x for older versions of eslint._

Import @lwc/eslint-plugin-lwc and use it in the plugins section of your configuration as shown below. Then configure the desired rules in the rules sections. Some of the syntax used in Lightning Web Components is not yet stage 4 (eg. class fields or decorators), and the out-of-the-box parser from ESLint doesn't support this syntax yet. In order to parse the LWC files properly, set the parser field to @babel/eslint-parser in the languageOptions section of the eslint config.

Example of eslint.config.js:

`js
const eslintPluginLwc = require('@lwc/eslint-plugin-lwc');
const babelParser = require('@babel/eslint-parser');

module.exports = [
{
languageOptions: {
parser: babelParser,
parserOptions: {
requireConfigFile: false,
babelOptions: {
parserOpts: {
plugins: [
'classProperties',
['decorators', { decoratorsBeforeExport: false }],
],
},
},
},
},
plugins: {
'@lwc/lwc': eslintPluginLwc, // https://github.com/salesforce/eslint-plugin-lwc
},
rules: {
'@lwc/lwc/no-deprecated': 'error',
'@lwc/lwc/valid-api': 'error',
'@lwc/lwc/no-document-query': 'error',
'@lwc/lwc/ssr-no-unsupported-properties': 'error',
},
},
];
`

$3

To enable working with TypeScript projects, install @babel/preset-typescript as a dependency add "typescript" to languageOptions.parserOptions.babelOptions.parserOpts.plugins in your eslint.config.js.

Example:

`js
const eslintPluginLwc = require('@lwc/eslint-plugin-lwc');
const babelParser = require('@babel/eslint-parser');

module.exports = [
{
languageOptions: {
parser: babelParser,
parserOptions: {
requireConfigFile: false,
babelOptions: {
parserOpts: {
plugins: [
'classProperties',
['decorators', { decoratorsBeforeExport: false }],
'typescript',
],
},
},
},
},
},
];
`

For more details about configuration please refer to the dedicated section in the ESLint documentation: https://eslint.org/docs/user-guide/configuring

Configurations

To choose from three configuration settings, install the eslint-config-lwc sharable configuration package.

$3

| Processor ID | Description |
| ----------------------------------- | ------------------------------------------------- |
| lwc/ssr | Lint only JavaScript files of SSR-able components |

Rules

$3

| Rule ID | Description | Fixable |
| -------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------ | ------- |
| lwc/consistent-component-name | ensure component class name matches file name | 🔧 |
| lwc/no-api-reassignments | prevent public property reassignments | |
| lwc/no-deprecated | disallow usage of deprecated LWC APIs | |
| lwc/newer-version-available | suggest newer versions of module imports when available | ✓ |
| lwc/no-document-query | disallow DOM query at the document level | |
| lwc/no-attributes-during-construction | disallow setting attributes during construction | |
| lwc/no-disallowed-lwc-imports | disallow importing unsupported APIs from the lwc package | |
| lwc/no-leading-uppercase-api-name | ensure public property doesn't start with an upper-case character | |
| lwc/no-unexpected-wire-adapter-usages | enforce wire adapters to be used with wire decorator | |
| lwc/no-unknown-wire-adapters | disallow usage of unknown wire adapters | |
| lwc/valid-api | validate api decorator usage | |
| lwc/valid-track | validate track decorator usage | |
| lwc/valid-wire | validate wire decorator usage | |
| lwc/valid-graphql-wire-adapter-callback-parameters | ensure graphql wire adapters are using 'errors' instead of 'error' | |
| lwc/no-host-mutation-in-connected-callback | disallow the host element mutation in 'connectedCallback' | |
| lwc/consistent-component-name | ensure component class name matches file name | 🔧 |
| lwc/no-api-reassignments | prevent public property reassignments | |
| lwc/no-deprecated | disallow usage of deprecated LWC APIs | |
| lwc/no-document-query | disallow DOM query at the document level | |
| lwc/no-attributes-during-construction | disallow setting attributes during construction | |
| lwc/no-disallowed-lwc-imports | disallow importing unsupported APIs from the lwc package | |
| lwc/no-leading-uppercase-api-name | ensure public property doesn't start with an upper-case character | |
| lwc/no-unexpected-wire-adapter-usages | enforce wire adapters to be used with wire decorator | |
| lwc/no-unknown-wire-adapters | disallow usage of unknown wire adapters | |
| lwc/valid-api | validate api decorator usage | |
| lwc/valid-track | validate track decorator usage | |
| lwc/valid-wire | validate wire decorator usage | |
| lwc/ssr-no-restricted-browser-globals | disallow access to global browser APIs during SSR | |
| lwc/ssr-no-unsupported-properties | disallow access of unsupported properties in SSR | |
| lwc/ssr-no-node-env | disallow usage of process.env.NODE_ENV in SSR | |
| lwc/ssr-no-disallowed-lwc-imports | restrict specific imports from the lwc package in SSR-able components | |
| lwc/valid-graphql-wire-adapter-callback-parameters | ensure graphql wire adapters are using 'errors' instead of 'error' | |
| lwc/ssr-no-host-mutation-in-connected-callback | disallow the host element mutation in 'connectedCallback' | |
| lwc/ssr-no-static-imports-of-user-specific-scoped-modules | disallow static imports of user-specific scoped modules in SSR-able components | |
| lwc/ssr-no-form-factor | disallow formFactor in SSR-able components | |

$3

| Rule ID | Description | Fixable |
| ---------------------------------------------------------------------------------- | ---------------------------------------------------------- | ------- |
| lwc/no-async-operation | restrict usage of async operations | |
| lwc/no-dupe-class-members | disallow duplicate class members | |
| lwc/no-inner-html | disallow usage of innerHTML | |
| lwc/no-template-children | prevent accessing the immediate children of this.template | |
| lwc/no-leaky-event-listeners | prevent event listeners from leaking memory | |
| lwc/prefer-custom-event | suggest usage of CustomEvent over Event` constructor | |
| lwc/ssr-no-unsupported-node-api | disallow unsupported Node API calls in SSR-able components | |

$3

Older browsers like IE11 run LWC in compatibility mode. For more information about browser performance, please refer to Supported Browsers in the Lightning Web Components Developer Guide.

| Rule ID | Description | Fixable |
| ---------------------------------------------------------- | ------------------------------------------- | ------- |
| lwc/no-async-await | disallow usage of the async-await syntax | |
| lwc/no-for-of | disallow usage of the for-of syntax | |
| lwc/no-rest-parameter | disallow usage of the rest parameter syntax | |

$3

| Rule ID | Replaced by |
| ------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------- |
| lwc/no-dupe-class-members | no-dupe-class-members(base eslint rule) |