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Rslint

    no-restricted-syntax

    Added in v0.5.2

    Configuration

    rslint.config.ts
    import { defineConfig, js } from '@rslint/core';

export default defineConfig([
  js.configs.recommended,
  {
    rules: {
      'no-restricted-syntax': 'error',
    },
  },
]);

    Rule Details

    Disallows specified syntax. The rule accepts a list of esquery selectors; any AST node matching one of the listed selectors triggers a diagnostic with either a default or user-supplied message.

    This is the catch-all rule for restricting language constructs (e.g. banning with, banning for-in, requiring named function declarations) without having to write a dedicated rule. The core selector grammar follows ESLint's esquery-based implementation.

    Examples of incorrect code for this rule:

    {
  "no-restricted-syntax": [
    "error",
    "FunctionExpression",
    "WithStatement"
  ]
}
    with (me) {
  dontMess();
}

const doSomething = function () {};

    Examples of correct code for the same configuration:

    me.dontMess();

function doSomething() {}

foo instanceof bar;

    Options

    The rule accepts an array of restriction entries. Each entry is either:

    • A bare string — the esquery selector. The diagnostic message is Using '<selector>' is not allowed..
    • An object { "selector": <string>, "message"?: <string> }. When message is provided it replaces the default text verbatim.
    {
  "no-restricted-syntax": [
    "error",
    {
      "selector": "CallExpression[callee.name='setTimeout']",
      "message": "Use the timer service instead of raw setTimeout."
    },
    "WithStatement"
  ]
}

    Supported selector forms

    The implementation covers the subset of esquery used in real-world ESLint configurations and in the upstream no-restricted-syntax test suite:

    • ESTree node names (e.g. Identifier, FunctionDeclaration, BinaryExpression).
    • Wildcard *.
    • Field selectors, including nested fields (e.g. Literal.key and .body.declarations.init).
    • Attribute selectors with presence ([label]), equality ([name="x"], [kind='using']), inequality (!=), numeric comparisons ([params.length>2]), numeric path segments ([arguments.0.type='Literal']), type(...), and regex matching ([regex.flags=/i/]). Attribute paths may inspect ESLint's parent link.
    • Combinators > (direct child), descendant whitespace, + (adjacent sibling), ~ (general sibling).
    • Pseudo-classes :is(), :matches(), :not(), :has(), :first-child, :last-child, :nth-child(N), :nth-last-child(N), and the semantic classes :statement, :expression, :declaration, :function, and :pattern.

    Differences from ESLint

    • ESLint rejects the configuration when a selector has invalid syntax. rslint ignores only that selector and continues with the remaining selectors, so its restriction is not enforced.
    • Selectors that target TS-ESTree-only nodes or fields may report fewer diagnostics than ESLint. For example, ClassBody > MethodDefinition produces no diagnostics in rslint because tsgo has no separate ClassBody node.
    • rslint ignores selectors using the ! subject marker, such as !IfStatement > BlockStatement, while ESLint accepts them.

    Original Documentation