useConsistentArrayType

Diagnostic Category: lint/style/useConsistentArrayType

TypeScript and TSX

Since: v1.5.0

Sources:

Same as: @typescript-eslint/array-type

Require consistently using either T[] or Array<T>

TypeScript provides two equivalent ways to define an array type: T[] and Array<T>. The two styles are functionally equivalent. Using the same style consistently across your codebase makes it easier for developers to read and understand array types.

Example

Invalid

let invalid: Array<foo>;

code-block.ts:1:14 lint/style/useConsistentArrayType  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Use shorthand T[] syntax instead of Array<T> syntax.
  
  > 1 │ let invalid: Array<foo>;
      │              ^^^^^^^^^^
    2 │ 
  
  ℹ Unsafe fix: Use shorthand T[] syntax to replace
  
    1   │ - let·invalid:·Array<foo>;
      1 │ + let·invalid:·foo[];
    2 2 │

let invalid: Promise<Array<string>>;

code-block.ts:1:22 lint/style/useConsistentArrayType  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Use shorthand T[] syntax instead of Array<T> syntax.
  
  > 1 │ let invalid: Promise<Array<string>>;
      │                      ^^^^^^^^^^^^^
    2 │ 
  
  ℹ Unsafe fix: Use shorthand T[] syntax to replace
  
    1   │ - let·invalid:·Promise<Array<string>>;
      1 │ + let·invalid:·Promise<string[]>;
    2 2 │

let invalid3: Array<Foo<Bar>>;

code-block.ts:1:15 lint/style/useConsistentArrayType  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Use shorthand T[] syntax instead of Array<T> syntax.
  
  > 1 │ let invalid3: Array<Foo<Bar>>;
      │               ^^^^^^^^^^^^^^^
    2 │ 
  
  ℹ Unsafe fix: Use shorthand T[] syntax to replace
  
    1   │ - let·invalid3:·Array<Foo<Bar>>;
      1 │ + let·invalid3:·Foo<Bar>[];
    2 2 │

Valid

const valid: Array<string | number> = ['a', 'b'];
const valid: Array<{ prop: string }> = [{ prop: 'a' }];
const valid: Array<() => void> = [() => {}];
const valid: MyType[] = ['a', 'b'];
const valid: string[] = ['a', 'b'];
const valid: readonly string[] = ['a', 'b'];

Options

The rule provides two options that help to specify what type of array declarations to use.

Default: “shorthand”

{
    "//": "...",
    "options": {
        "syntax": "shorthand"
    }
}

Syntax

By default, all array declarations will be converted to T[] or readonly T[], which it means shorthand, or if the options is set to the “generic”, that all will converted to Array<T> or ReadonlyArray<T>.