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Rslint

    no-new-array

    Unreleased

    Configuration

    PresetConfigured Value
    ✅ unicornPlugin.configs.recommended"error"
    rslint.config.ts
    import { defineConfig, unicornPlugin } from '@rslint/core';

export default defineConfig([
  unicornPlugin.configs.recommended,
  {
    rules: {
      'unicorn/no-new-array': 'error',
    },
  },
]);

    Rule Details

    Disallow new Array() with one argument because it is unclear whether the argument is an array length or a single element.

    The rule complements no-array-constructor, which handles constructors with zero or multiple arguments.

    Examples of incorrect code:

    const array = new Array(onlyElement);
const items = new Array(...values);

    Examples of correct code:

    const array = [onlyElement];
const items = [...values];

    Known non-numeric arguments can be automatically replaced with an array literal. A spread argument receives an editor suggestion. Comments inside the constructor prevent both kinds of edits.

    Numeric and unknown arguments are reported without edits. new Array(3) creates three holes, while Array.from({ length: 3 }) creates three undefined elements; these behave differently with methods such as filter().

    Options

    This rule has no options. It provides automatic fixes and editor suggestions and is enabled at error severity in unicornPlugin.configs.recommended.

    Differences from upstream

    When Array refers to a local declaration, parameter, or import, or is disabled through languageOptions.globals, rslint reports the diagnostic without a fix or suggestion. This preserves custom constructor behavior, such as setting result.value in new Array('x').

    Constructors with explicit TypeScript type arguments also receive no fix or suggestion. For example, changing new Array<string | null>('x') to ['x'] would infer string[] and reject a later push(null). To use a literal while retaining the element type, write const values: (string | null)[] = ['x'];.

    For built-in objects and functions, such as new Array(Math) or new Array(Array), rslint reports the same diagnostic but does not offer upstream's automatic fix. This also applies to their typeof expressions and to new Array(typeof Symbol.iterator).

    Replace these constructors with array literals manually, for example [Math] or [typeof Array], to make the intended single element explicit. Well-known symbols are supported directly: new Array(Symbol.iterator) is automatically fixed to [Symbol.iterator].

    Original Documentation