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sort-type-constituents

Enforce constituents of a type union/intersection to be sorted alphabetically.

🔧

Some problems reported by this rule are automatically fixable by the --fix ESLint command line option.

💡

Some problems reported by this rule are manually fixable by editor suggestions.

Sorting union (|) and intersection (&) types can help:

  • keep your codebase standardized
  • find repeated types
  • reduce diff churn

This rule reports on any types that aren't sorted alphabetically.

Types are sorted case-insensitively and treating numbers like a human would, falling back to character code sorting in case of ties.

.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/sort-type-constituents": "warn"
  }
};

Examples​

type T1 = B | A;

type T2 = { b: string } & { a: string };

type T3 = [1, 2, 4] & [1, 2, 3];

type T4 =
  | [1, 2, 4]
  | [1, 2, 3]
  | { b: string }
  | { a: string }
  | (() => void)
  | (() => string)
  | 'b'
  | 'a'
  | 'b'
  | 'a'
  | readonly string[]
  | readonly number[]
  | string[]
  | number[]
  | B
  | A
  | string
  | any;

Options​

This rule accepts an options object with the following properties:

interface Options {
  /**
   * Whether to check intersection types.
   */
  checkIntersections?: boolean;
  /**
   * Whether to check union types.
   */
  checkUnions?: boolean;
  /**
   * Ordering of the groups.
   */
  groupOrder?: (
    | "conditional"
    | "function"
    | "import"
    | "intersection"
    | "keyword"
    | "nullish"
    | "literal"
    | "named"
    | "object"
    | "operator"
    | "tuple"
    | "union"
  )[];
}

const defaultOptions: Options = [
  {
    checkIntersections: true,
    checkUnions: true,
    groupOrder: [
      "named",
      "keyword",
      "operator",
      "literal",
      "function",
      "import",
      "conditional",
      "object",
      "tuple",
      "intersection",
      "union",
      "nullish",
    ],
  },
];

groupOrder​

Each constituent of the type is placed into a group, and then the rule sorts alphabetically within each group. The ordering of groups is determined by this option.

  • conditional - Conditional types (A extends B ? C : D)
  • function - Function and constructor types (() => void, new () => type)
  • import - Import types (import('path'))
  • intersection - Intersection types (A & B)
  • keyword - Keyword types (any, string, etc)
  • literal - Literal types (1, 'b', true, etc)
  • named - Named types (A, A['prop'], B[], Array<C>)
  • object - Object types ({ a: string }, { [key: string]: number })
  • operator - Operator types (keyof A, typeof B, readonly C[])
  • tuple - Tuple types ([A, B, C])
  • union - Union types (A | B)
  • nullish - null and undefined

Resources​