.eslintrc.json

{
    "root": true,
    "parser": "@typescript-eslint/parser",
    "parserOptions": {
        "warnOnUnsupportedTypeScriptVersion": false,
        "sourceType": "module"
    },
    "env": {
        "browser": false,
        "node": true,
        "es6": true
    },
    "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:@typescript-eslint/stylistic"
    ],
    "plugins": [
        "@typescript-eslint",
        "no-null",
        "eslint-plugin-local",
        "simple-import-sort"
    ],
    "ignorePatterns": [
        "**/node_modules/**",
        "/built/**",
        "/tests/**",
        "/lib/**",
        "/src/lib/*.generated.d.ts",
        "/scripts/**/*.js",
        "/scripts/**/*.d.*",
        "/internal/**",
        "/coverage/**"
    ],
    "rules": {
        // eslint
        "dot-notation": "error",
        "eqeqeq": "error",
        "no-caller": "error",
        "no-constant-condition": ["error", { "checkLoops": false }],
        "no-eval": "error",
        "no-extra-bind": "error",
        "no-new-func": "error",
        "no-new-wrappers": "error",
        "no-return-await": "error",
        "no-restricted-globals": [
            "error",
            { "name": "setTimeout" },
            { "name": "clearTimeout" },
            { "name": "setInterval" },
            { "name": "clearInterval" },
            { "name": "setImmediate" },
            { "name": "clearImmediate" }
        ],
        "no-template-curly-in-string": "error",
        "no-throw-literal": "error",
        "no-undef-init": "error",
        "no-var": "error",
        "object-shorthand": "error",
        "prefer-const": "error",
        "prefer-object-spread": "error",
        "unicode-bom": ["error", "never"],

        // Enabled in eslint:recommended, but not applicable here
        "no-extra-boolean-cast": "off",
        "no-case-declarations": "off",
        "no-cond-assign": "off",
        "no-control-regex": "off",
        "no-inner-declarations": "off",

        // @typescript-eslint/eslint-plugin
        "@typescript-eslint/naming-convention": [
            "error",
            { "selector": "typeLike", "format": ["PascalCase"], "filter": { "regex": "^(__String|[A-Za-z]+_[A-Za-z]+)$", "match": false } },
            { "selector": "interface", "format": ["PascalCase"], "custom": { "regex": "^I[A-Z]", "match": false }, "filter": { "regex": "^I(Arguments|TextWriter|O([A-Z][a-z]+[A-Za-z]*)?)$", "match": false } },
            { "selector": "variable", "format": ["camelCase", "PascalCase", "UPPER_CASE"], "leadingUnderscore": "allow", "filter": { "regex": "^(_{1,2}filename|_{1,2}dirname|_+|[A-Za-z]+_[A-Za-z]+)$", "match": false } },
            { "selector": "function", "format": ["camelCase", "PascalCase"], "leadingUnderscore": "allow", "filter": { "regex": "^[A-Za-z]+_[A-Za-z]+$", "match": false } },
            { "selector": "parameter", "format": ["camelCase"], "leadingUnderscore": "allow", "filter": { "regex": "^(_+|[A-Za-z]+_[A-Z][a-z]+)$", "match": false } },
            { "selector": "method", "format": ["camelCase", "PascalCase"], "leadingUnderscore": "allow", "filter": { "regex": "^([0-9]+|[A-Za-z]+_[A-Za-z]+)$", "match": false } },
            { "selector": "memberLike", "format": ["camelCase"], "leadingUnderscore": "allow", "filter": { "regex": "^([0-9]+|[A-Za-z]+_[A-Za-z]+)$", "match": false } },
            { "selector": "enumMember", "format": ["camelCase", "PascalCase"], "leadingUnderscore": "allow", "filter": { "regex": "^[A-Za-z]+_[A-Za-z]+$", "match": false } },
            { "selector": "property", "format": null }
        ],

        "@typescript-eslint/unified-signatures": "error",
        "no-unused-expressions": "off",
        "@typescript-eslint/no-unused-expressions": ["error", { "allowTernary": true }],

        // Rules enabled in typescript-eslint configs that are not applicable here
        "@typescript-eslint/ban-ts-comment": "off",
        "@typescript-eslint/class-literal-property-style": "off",
        "@typescript-eslint/consistent-indexed-object-style": "off",
        "@typescript-eslint/no-duplicate-enum-values": "off",
        "@typescript-eslint/no-empty-function": "off",
        "@typescript-eslint/no-namespace": "off",
        "@typescript-eslint/no-non-null-asserted-optional-chain": "off",
        "@typescript-eslint/no-var-requires": "off",
        "@typescript-eslint/no-empty-interface": "off",
        "@typescript-eslint/no-explicit-any": "off",
        "@typescript-eslint/ban-types": [
            "error",
            {
                "extendDefaults": true,
                "types": {
                    // This is theoretically good, but ts-eslint appears to mistake our declaration of Symbol for the global Symbol type.
                    // See: https://github.com/typescript-eslint/typescript-eslint/issues/7306
                    "Symbol": false,
                    "{}": false // {} is a totally useful and valid type.
                }
            }
        ],
        "@typescript-eslint/no-unused-vars": [
            "error",
            {
                // Ignore: (solely underscores | starting with exactly one underscore)
                "argsIgnorePattern": "^(_+$|_[^_])",
                "varsIgnorePattern": "^(_+$|_[^_])"
            }
        ],

        // Pending https://github.com/typescript-eslint/typescript-eslint/issues/4820
        "@typescript-eslint/prefer-optional-chain": "off",

        // scripts/eslint/rules
        "local/only-arrow-functions": [
            "error",
            {
                "allowNamedFunctions": true,
                "allowDeclarations": true
            }
        ],
        "local/argument-trivia": "error",
        "local/no-in-operator": "error",
        "local/debug-assert": "error",
        "local/no-keywords": "error",
        "local/jsdoc-format": "error",

        // eslint-plugin-no-null
        "no-null/no-null": "error",

        // eslint-plugin-simple-import-sort
        "simple-import-sort/imports": "error",
        "simple-import-sort/exports": "error"
    },
    "overrides": [
        // By default, the ESLint CLI only looks at .js files. But, it will also look at
        // any files which are referenced in an override config. Most users of typescript-eslint
        // get this behavior by default by extending a recommended typescript-eslint config, which
        // just so happens to override some core ESLint rules. We don't extend from any config, so
        // explicitly reference TS files here so the CLI picks them up.
        //
        // ESLint in VS Code will lint any opened file (so long as it's not eslintignore'd), so
        // that will work regardless of the below.
        //
        // The same applies to mjs files; ESLint appears to not scan those either.
        { "files": ["*.ts", "*.mts", "*.cts", "*.mjs", "*.cjs"] },
        {
            "files": ["*.mjs", "*.mts"],
            "rules": {
                // These globals don't exist outside of CJS files.
                "no-restricted-globals": [
                    "error",
                    { "name": "__filename" },
                    { "name": "__dirname" },
                    { "name": "require" },
                    { "name": "module" },
                    { "name": "exports" }
                ]
            }
        },
        {
            // These files contain imports in a specific order that are generally unsafe to modify.
            "files": ["**/_namespaces/**"],
            "rules": {
                "simple-import-sort/imports": "off",
                "simple-import-sort/exports": "off"
            }
        }
    ]
}