#no-unsupported-features/es-syntax

#Configuration

import { defineConfig, nodePlugin } from '@rslint/core';

export default defineConfig([
  nodePlugin.configs.recommended,
  {
    rules: {
      'node/no-unsupported-features/es-syntax': 'error',
    },
  },
]);

Disallows ECMAScript features that are unavailable in part of the configured Node.js version range.

#Rule details

The rule checks syntax such as optional chaining, dynamic imports, class fields, static blocks, regular expressions, and top-level await. It also checks the built-in APIs included in the upstream feature table, such as Object.hasOwn and Array.prototype.toSorted. Local bindings that shadow built-in globals are excluded.

With version: ">=16.0.0", these examples are incorrect:

class Cache {
  static {
    this.entries = new Map();
  }
}

Object.hasOwn(object, key);
[3, 1, 2].toSorted();

These features require Node.js 16.11, 16.9, and 20 respectively. Set a version range that supports the features you use, or use older syntax and APIs:

class Cache {}
Cache.entries = new Map();

Object.prototype.hasOwnProperty.call(object, key);
[3, 1, 2].slice().sort();

The rule does not provide automatic fixes or suggestions.

#Options

export default [
  {
    plugins: ["node"],
    rules: {
      "node/no-unsupported-features/es-syntax": [
        "error",
        {
          version: ">=16.0.0",
          ignores: [],
        },
      ],
    },
  },
];

#version

The first valid Node.js version range is used, in this order:

1. The rule's version option.
2. settings.n.version, then settings.node.version.
3. The nearest valid package.json's engines.node.
4. Its devEngines.runtime entry named node.
5. The default, >=16.0.0.

Every version in the range must support a feature. For example, dynamic imports support ^12.17.0 || >=13.2.0, but >=12.17.0 also includes unsupported Node.js 13.0 and 13.1. Strict mode is taken into account for features whose support in older Node.js releases depends on it.

#ignores

An array of features to skip, for example when a transpiler or polyfill supplies them. Each feature accepts its upstream rule name, the name without no-, and the camelCase spelling: no-optional-chaining, optional-chaining, and optionalChaining are equivalent. Legacy aliases such as new.target, regexpLookbehind, and trailingCommasInFunctions are also supported.

See the upstream feature table for the complete list and version ranges.

#Shared settings

settings.node.version sets the target for multiple Node rules. The upstream settings.n.version spelling remains supported and takes precedence when both are set.

settings["es-x"].aggressive: true also reports prototype properties on receivers whose type cannot be determined. By default, only recognized receivers are reported. When a TypeScript project is configured, available type information is used to recognize receivers, including unions and constrained generics.

#Differences from upstream

• With version: ">=15 || >20 <15", dynamic imports and nullish coalescing are accepted: the impossible >20 <15 alternative matches no Node.js version. Upstream reports both features. Use >=15 to get the same result in both tools.

#References

• Upstream documentation
• Upstream rule