Official ESLint rules for Lightning Web Components (LWC).

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

Add @lwc/eslint-plugin-lwc to the plugins section of your configuration. 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.

Example of .eslintrc:

{
    "parser": "@babel/eslint-parser",
    "parserOptions": {
        "requireConfigFile": false,
        "babelOptions": {
            "parserOpts": {
                "plugins": ["classProperties", ["decorators", { "decoratorsBeforeExport": false }]]
            }
        }
    },

    "plugins": ["@lwc/eslint-plugin-lwc"],

    "rules": {
        "@lwc/lwc/no-deprecated": "error",
        "@lwc/lwc/valid-api": "error",
        "@lwc/lwc/no-document-query": "error"
    }
}

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

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

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.