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sort-type-union-intersection-members

Enforces that members of a type union/intersection are sorted alphabetically.

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

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

Rule Details

Sorting within each group is done using the following code:

const collator = new Intl.Collator('en', {
sensitivity: 'base',
numeric: true,
});

function compare(a, b) {
return collator.compare(a, b) || (a < b ? -1 : a > b ? 1 : 0);
}

In other words, the types are sorted alphabetically, case-insensitively and treating numbers like a human would, falling back to character code sorting in case of ties.

Examples of code for this rule:

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

type Options = {
// true to check intersection types, false otherwise
checkIntersections?: boolean;
// true to check union types, false otherwise
checkUnions?: boolean;
// the ordering of the groups
groupOrder?: (
| 'conditional'
| 'function'
| 'import'
| 'intersection'
| 'keyword'
| 'literal'
| 'named'
| 'object'
| 'operator'
| 'tuple'
| 'union'
| 'nullish'
)[];
};

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

groupOrder

Each member 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

Attributes

  • Configs:
    • ✅ Recommended
    • 🔒 Strict
  • 🔧 Fixable
  • 💭 Requires type information