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useConsistentArrayType (since v1.5.0)

Diagnostic Category: lint/style/useConsistentArrayType

Sources:

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

Section titled Example

Invalid

Section titled Invalid
let invalid: Array<foo>;
style/useConsistentArrayType.js: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>>;
style/useConsistentArrayType.js: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>>;
style/useConsistentArrayType.js: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

Section titled 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

Section titled Options

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

Default: “shorthand”

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

Syntax

Section titled 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>.

Section titled Related links