.eslintrc

{
    "root": true,
    // ...
    "parserOptions": {
        // ...

        "extraFileExtensions": [".svelte"],
        // This is a required setting in `@typescript-eslint/parser` v4.24.0.
        "sourceType": "module"
    },
    "overrides": [
        {
            "files": ["*.svelte"],
            "parser": "svelte-eslint-parser",
            // Parse the `<script>` in `.svelte` as TypeScript by adding the following configuration.
            "parserOptions": {
                "parser": "@typescript-eslint/parser"
            }
        }
        // ...
    ],
    "parser": "@typescript-eslint/parser",
    "env": {
        "node": true
    },
    "plugins": ["@typescript-eslint"],
    "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/eslint-recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:svelte/recommended"
    ],
    "rules": {
        "svelte/valid-compile": ["error", { "ignoreWarnings": true }],
        "@typescript-eslint/ban-ts-comment": "off",
        "no-prototype-builtins": "off",
        "@typescript-eslint/no-empty-function": "off",
        "no-console": "error",
        "@typescript-eslint/no-unused-vars": ["error"]
    }
}