#no-restricted-syntax

#Configuration

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 selector grammar matches ESLint's, so selectors authored against ESLint's no-restricted-syntax configuration are expected to work unchanged in rslint.

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 *.
• Class selectors .field (e.g. Literal.key).
• Attribute selectors with presence ([label]), equality ([name="x"], [kind='using']), inequality (!=), numeric comparisons ([params.length>2]), and regex matching ([regex.flags=/i/]).
• 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).

#Original Documentation

• ESLint no-restricted-syntax