eslint-config-ts-strict/rules/errors.js

Very strict ESLint config for projects using TypeScript, React and Prettier. ESLint v9 flat config only. Formatting rules disabled to prevent Prettier conflicts.

export default {
  rules: {
    // Enforce “for” loop update clause moving the counter in the right direction
    // https://eslint.org/docs/rules/for-direction
    "for-direction": "error",

    // Enforces that a return statement is present in property getters
    // https://eslint.org/docs/rules/getter-return
    "getter-return": ["error", { allowImplicit: true }],

    // disallow using an async function as a Promise executor
    // https://eslint.org/docs/rules/no-async-promise-executor
    "no-async-promise-executor": "error",

    // Disallow await inside of loops
    // https://eslint.org/docs/rules/no-await-in-loop
    "no-await-in-loop": "off",

    // Disallow comparisons to negative zero
    // https://eslint.org/docs/rules/no-compare-neg-zero
    "no-compare-neg-zero": "error",

    // disallow assignment in conditional expressions
    "no-cond-assign": ["error", "always"],

    // disallow use of console
    "no-console": "warn",

    // disallow use of constant expressions in conditions
    "no-constant-condition": "warn",

    // disallow control characters in regular expressions
    "no-control-regex": "error",

    // disallow use of debugger
    "no-debugger": "error",

    // disallow duplicate arguments in functions
    "no-dupe-args": "error",

    // Disallow duplicate conditions in if-else-if chains
    // https://eslint.org/docs/rules/no-dupe-else-if
    "no-dupe-else-if": "error",

    // disallow duplicate keys when creating object literals
    "no-dupe-keys": "error",

    // disallow a duplicate case label.
    "no-duplicate-case": "error",

    // disallow empty statements
    "no-empty": "error",

    // disallow the use of empty character classes in regular expressions
    "no-empty-character-class": "error",

    // disallow assigning to the exception in a catch block
    "no-ex-assign": "error",

    // disallow double-negation boolean casts in a boolean context
    // https://eslint.org/docs/rules/no-extra-boolean-cast
    "no-extra-boolean-cast": "error",

    // disallow overwriting functions written as function declarations
    "no-func-assign": "error",

    // https://eslint.org/docs/rules/no-import-assign
    "no-import-assign": "error",

    // disallow function or variable declarations in nested blocks
    "no-inner-declarations": "error",

    // disallow invalid regular expression strings in the RegExp constructor
    "no-invalid-regexp": "error",

    // disallow irregular whitespace outside of strings and comments
    "no-irregular-whitespace": "error",

    // Disallow characters which are made with multiple code points in character class syntax
    // https://eslint.org/docs/rules/no-misleading-character-class
    "no-misleading-character-class": "error",

    // disallow the use of object properties of the global object (Math and JSON) as functions
    "no-obj-calls": "error",

    // Disallow returning values from Promise executor functions
    // https://eslint.org/docs/rules/no-promise-executor-return
    "no-promise-executor-return": "error",

    // disallow use of Object.prototypes builtins directly
    // https://eslint.org/docs/rules/no-prototype-builtins
    "no-prototype-builtins": "error",

    // disallow multiple spaces in a regular expression literal
    "no-regex-spaces": "error",

    // Disallow returning values from setters
    // https://eslint.org/docs/rules/no-setter-return
    "no-setter-return": "error",

    // disallow sparse arrays
    "no-sparse-arrays": "error",

    // Disallow template literal placeholder syntax in regular strings
    // https://eslint.org/docs/rules/no-template-curly-in-string
    "no-template-curly-in-string": "error",

    // Avoid code that looks like two expressions but is actually one
    // https://eslint.org/docs/rules/no-unexpected-multiline
    "no-unexpected-multiline": "error",

    // disallow unreachable statements after a return, throw, continue, or break statement
    "no-unreachable": "error",

    // Disallow loops with a body that allows only one iteration
    // https://eslint.org/docs/rules/no-unreachable-loop
    "no-unreachable-loop": [
      "error",
      {
        ignore: [], // WhileStatement, DoWhileStatement, ForStatement, ForInStatement, ForOfStatement
      },
    ],

    // disallow return/throw/break/continue inside finally blocks
    // https://eslint.org/docs/rules/no-unsafe-finally
    "no-unsafe-finally": "error",

    // disallow negating the left operand of relational operators
    // https://eslint.org/docs/rules/no-unsafe-negation
    "no-unsafe-negation": "error",

    // disallow use of optional chaining in contexts where the undefined value is not allowed
    // https://eslint.org/docs/rules/no-unsafe-optional-chaining
    "no-unsafe-optional-chaining": [
      "error",
      { disallowArithmeticOperators: true },
    ],

    // Disallow Unused Private Class Members
    // https://eslint.org/docs/rules/no-unused-private-class-members
    // TODO: enable once eslint 7 is dropped (which is semver-major)
    "no-unused-private-class-members": "off",

    // Disallow useless backreferences in regular expressions
    // https://eslint.org/docs/rules/no-useless-backreference
    "no-useless-backreference": "error",

    // disallow negation of the left operand of an in expression
    // deprecated in favor of no-unsafe-negation
    "no-negated-in-lhs": "off",

    // Disallow assignments that can lead to race conditions due to usage of await or yield
    // https://eslint.org/docs/rules/require-atomic-updates
    // note: not enabled because it is very buggy
    "require-atomic-updates": "off",

    // disallow comparisons with the value NaN
    "use-isnan": "error",

    // Disallow assignments that are useless and don't affect the value of a variable
    // https://eslint.org/docs/rules/no-useless-assignment
    "no-useless-assignment": "error",

    // ensure JSDoc comments are valid
    // https://eslint.org/docs/rules/valid-jsdoc
    "valid-jsdoc": "off",

    // ensure that the results of typeof are compared against a valid string
    // https://eslint.org/docs/rules/valid-typeof
    "valid-typeof": ["error", { requireStringLiterals: true }],
  },
};