eslint-plugin-perfectionist/docs/content/rules/sort-interfaces.mdx at b49f289e80683d96af4ca4c2e639364329598f5d · hugop95/eslint-plugin-perfectionist

title

sort-interfaces

description

Enforce sorting of TypeScript interface properties for a clear and predictable code structure. Use this ESLint rule to maintain consistency in your interfaces

shortDescription

Enforce sorted interface properties

keywords

eslint

sort interfaces

eslint rule

coding standards

code quality

javascript linting

typescript interfaces sorting

import CodeExample from '../../components/CodeExample.svelte' import Important from '../../components/Important.astro' import CodeTabs from '../../components/CodeTabs.svelte' import dedent from 'dedent'

Enforce sorted TypeScript interface properties.

Sorting interface properties in TypeScript provides a clear and predictable structure to the codebase. This rule helps developers locate various properties defined within an interface more easily, promoting consistency and enabling efficient maintenance and collaboration.

Additionally, it ensures that property comments are sorted along with the properties themselves, preserving documentation clarity.

If you use the [`adjacent-overload-signatures`](https://typescript-eslint.io/rules/adjacent-overload-signatures) rule from the [`@typescript-eslint/eslint-plugin`](https://typescript-eslint.io) plugin, it is highly recommended to [disable it](https://eslint.org/docs/latest/use/configure/rules#using-configuration-files-1) to avoid conflicts.

It's safe. If you document interface properties line by line, property comments will also be sorted.

Try it out

<CodeExample alphabetical={dedent` interface Address { apartmentNumber?: string city: string country: string postalCode: string street: string }

interface User {
  address: Address
  email: string
  firstName: string
  id: string
  login: string
  phoneNumber?: string
  roles: string[]
}

interface Project {
  budget: number
  description: string
  id: string
  name: string
  projectTeamMembers: User[]
  startDate: Date
  status: string
}

} lineLength={dedent interface Address { apartmentNumber?: string postalCode: string country: string street: string city: string }

interface User {
  phoneNumber?: string
  firstName: string
  address: Address
  roles: string[]
  email: string
  login: string
  id: string
}

interface Project {
  projectTeamMembers: User[]
  description: string
  startDate: Date
  budget: number
  status: string
  name: string
  id: string
}

} initial={dedent interface Address { street: string city: string country: string postalCode: string apartmentNumber?: string }

interface User {
  firstName: string
  email: string
  roles: string[]
  login: string
  phoneNumber?: string
  address: Address
  id: string
}

interface Project {
  startDate: Date
  budget: number
  description: string
  id: string
  projectTeamMembers: User[]
  name: string
  status: string
}

`} client:load lang="tsx" />

Options

This rule accepts an options object with the following properties:

type

_{default: 'alphabetical'}

Specifies the sorting method.

'alphabetical' — Sort items alphabetically (e.g., “a” < “b” < “c”) using localeCompare.
'natural' — Sort items in a natural order (e.g., “item2” < “item10”).
'line-length' — Sort items by code line length (shorter lines first).
'custom' — Sort items using the alphabet specified in the alphabet option.
'unsorted' — Do not sort items. grouping and newlines behavior are still enforced.

order

_{default: 'asc'}

Specifies whether to sort items in ascending or descending order.

'asc' — Sort items in ascending order (A to Z, 1 to 9).
'desc' — Sort items in descending order (Z to A, 9 to 1).

fallbackSort

_{type:
```ts
{
type:
| 'alphabetical'
| 'natural'
| 'line-length'
| 'custom'
| 'subgroup-order'
| 'unsorted'
order?: 'asc' | 'desc'
sortBy?: 'name' | 'value'
}
```} _{default: `{ type: 'unsorted' }`}

Specifies fallback sort options for elements that are equal according to the primary sort type.

You can also sort by subgroup order (nested groups in the groups option) using subgroup-order.

Example: enforce alphabetical sort between two elements with the same length.

{
  type: 'line-length',
  order: 'desc',
  fallbackSort: { type: 'alphabetical', order: 'asc' }
}

alphabet

_{default: ''}

Used only when the type option is set to 'custom'. Specifies the custom alphabet for sorting.

Use the Alphabet utility class from eslint-plugin-perfectionist/alphabet to quickly generate a custom alphabet.

Example: 0123456789abcdef...

ignoreCase

_{default: true}

Specifies whether sorting should be case-sensitive.

true — Ignore case when sorting alphabetically or naturally (e.g., “A” and “a” are the same).
false — Consider case when sorting (e.g., “a” comes before “A”).

specialCharacters

_{default: 'keep'}

Specifies whether to trim, remove, or keep special characters before sorting.

'keep' — Keep special characters when sorting (e.g., “_a” comes before “a”).
'trim' — Trim special characters when sorting alphabetically or naturally (e.g., “_a” and “a” are the same).
'remove' — Remove special characters when sorting (e.g., “/a/b” and “ab” are the same).

locales

_{default: 'en-US'}

Specifies the sorting locales. Refer To String.prototype.localeCompare() - locales.

string — A BCP 47 language tag (e.g. 'en', 'en-US', 'zh-CN').
string[] — An array of BCP 47 language tags.

sortBy

_{default: 'name'}

Controls whether sorting should be done only using the interface's values.

name — Use interface types keys.
value — Use the values of properties. Non-properties will not have an enforced sort order.

Example

interface User {
  createdAt: Date
  lastLoginAt: Date
  _id: ObjectId
  groupId: ObjectId
  city: string
}

sortBy option configuration:

{
  sortBy: 'value',
}

partitionByComment

_{default: false}

Enables the use of comments to separate the properties of interfaces into logical groups. This can help in organizing and maintaining large interfaces by creating partitions within the interface based on comments.

true — All comments will be treated as delimiters, creating partitions.
false — Comments will not be used as delimiters.
RegExpPattern = string | { pattern: string; flags: string} — A regexp pattern to specify which comments should act as delimiters.
RegExpPattern[] — A list of regexp patterns to specify which comments should act as delimiters.
{ block: boolean | RegExpPattern | RegExpPattern[]; line: boolean | RegExpPattern | RegExpPattern[] } — Specify which block and line comments should act as delimiters.

partitionByNewLine

_{default: false}

When true, the rule will not sort the members of an interface if there is an empty line between them. This helps maintain the defined order of logically separated groups of members.

interface User {
  // Group 1
  firstName: string;
  lastName: string;

  // Group 2
  age: number;
  birthDate: Date;

  // Group 3
  address: string;
  phone?: string;
}

Each group of members (separated by empty lines) is treated independently, and the order within each group is preserved.

newlinesBetween

_{type: `number | 'ignore'`} _{default: `'ignore'`}

Specifies how to handle newlines between groups.

'ignore' — Do not report errors related to newlines.
0 — No newlines are allowed.
Any other number — Enforce this number of newlines between each group.

You can also enforce the newline behavior between two specific groups through the groups option.

This option is only applicable when partitionByNewLine is false.

newlinesInside

_{type: `number | 'ignore' | 'newlinesBetween'`} _{default: `'newlinesBetween'`}

Specifies how to handle newlines inside groups.

'ignore' — Do not report errors related to newlines.
'newlinesBetween' — [DEPRECATED] If newlinesBetween is 'ignore', then 'ignore', otherwise 0.
0 — No newlines are allowed.
Any other number — Enforce this number of newlines between each element of the same group.

You can also enforce the newline behavior inside a given group through the groups or customGroups options.

This option is only applicable when partitionByNewLine is false.

useConfigurationIf

_{type:
```ts
{
allNamesMatchPattern?:
| string
| string[]
| { pattern: string; flags: string }
| { pattern: string; flags: string }[]
declarationMatchesPattern?:
| string
| string[]
| { pattern: string; flags: string }
| { pattern: string; flags: string }[]
declarationCommentMatchesPattern?:
| string
| string[]
| { pattern: string; flags: string }
| { pattern: string; flags: string }[]
hasNumericKeysOnly?: boolean
matchesAstSelector?: string
}
```}

Specifies filters to match a particular options configuration for a given interface.

The first matching options configuration will be used. If no configuration matches, the default options configuration will be used.

allNamesMatchPattern — A regexp pattern that all keys must match.

Example configuration:

{
  'perfectionist/sort-interfaces': [
    'error',
    {
      groups: ['r', 'g', 'b'], // Sort colors types by RGB
      customGroups: [
        {
          groupName: 'r',
          elementNamePattern: '^r$',
        },
        {
          groupName: 'g',
          elementNamePattern: '^g$',
        },
        {
          groupName: 'b',
          elementNamePattern: '^b$',
        },
      ],
      useConfigurationIf: {
        allNamesMatchPattern: '^[rgb]$',
      },
    },
    {
      type: 'alphabetical' // Fallback configuration
    }
  ],
}

declarationMatchesPattern — A regexp pattern that the interface declaration must match.

Example configuration:

{
  'perfectionist/sort-interfaces': [
    'error',
    {
      type: 'unsorted', // Do not sort Metadata interfaces
      useConfigurationIf: {
        declarationMatchesPattern: '*Metadata$',
      },
    },
    {
      type: 'alphabetical' // Fallback configuration
    }
  ],
}

declarationCommentMatchesPattern — A regexp pattern to specify which comments above the interface declaration should match.

Example configuration:

{
  'perfectionist/sort-interfaces': [
    'error',
    {
      type: 'unsorted', // Don't sort interfaces with a "do not sort" comment
      useConfigurationIf: {
        declarationCommentMatchesPattern: '^do not sort$',
      },
    },
    {
      type: 'alphabetical' // Fallback configuration
    }
  ],
}

hasNumericKeysOnly — If true, matches only interfaces that have exclusively numeric keys.

This option only detects unquoted numeric literal keys (e.g., 1, 42). Quoted strings like "1", array-wrapped keys like [1], or computed expressions are not detected as numeric keys.

Example configuration:

{
  'perfectionist/sort-interfaces': [
    'error',
    {
      type: 'natural', // Sort numeric keys naturally (by numeric value)
      useConfigurationIf: {
        hasNumericKeysOnly: true,
      },
    },
    {
      type: 'alphabetical' // Fallback configuration
    }
  ],
}

matchesAstSelector — An AST selector matching a TSInterfaceDeclaration node. To avoid unexpected behavior, do not use :exit or :enter pseudo-selectors.

groups

_{type:
```ts
Array<
| string
| string[]
| { newlinesBetween: number | 'ignore' }
| {
group: string | string[];
type?: 'alphabetical' | 'natural' | 'line-length' | 'custom' | 'unsorted';
order?: 'asc' | 'desc';
fallbackSort?: { type: string; order?: 'asc' | 'desc'; sortBy?: 'name' | 'value' };
sortBy?: 'name' | 'value'
newlinesInside?: number | 'ignore';
}
>
```} _{default: `[]`}

Specifies a list of interface member groups for sorting. Groups help organize members into categories, making your interfaces more readable and maintainable.

Each interface member will be assigned a single group specified in the groups option (or the unknown group if no match is found). The order of items in the groups option determines how groups are ordered.

Within a given group, members will be sorted according to the type, order, ignoreCase, etc. options.

Individual groups can be combined together by placing them in an array. The order of groups in that array does not matter. All members of the groups in the array will be sorted together as if they were part of a single group.

Predefined groups are characterized by a single selector and potentially multiple modifiers. You may enter modifiers in any order, but the selector must always come at the end.

Example

interface User {
  firstName: string // unknown
  lastName: string  // unknown
  username: string  // unknown
  job: {            // multiline-member
    // Stuff about job
  }
  localization: {   // multiline-member
    // Stuff about localization
  }
}

groups option configuration:

{
  groups: [
    'unknown',
    'method',
    'multiline-member',
  ]
}

Index-signatures

Selectors: 'index-signature', 'member'.
Modifiers: 'required', 'optional', 'multiline'.
Example: 'optional-index-signature', 'index-signature', 'member'.

Methods

Selectors: 'method', 'member'.
Modifiers: 'required', 'optional', 'multiline'.
Example: 'optional-multiline-method', 'method', 'member'.

Properties

Selectors: 'property', 'member'.
Modifiers: 'required', 'optional', 'multiline'.
Example: 'optional-property', 'property', 'member'.

Scope of the `required` modifier

Elements that are not optional will be matched with the required modifier, even if the keyword is not present.

Important notes

The `unknown` group

Members that don't fit into any group specified in the groups option will be placed in the unknown group. If the unknown group is not specified in the groups option, it will automatically be added to the end of the list.

Behavior when multiple groups match an element

The lists of modifiers above are sorted by importance, from most to least important. In case of multiple groups matching an element, the following rules will be applied:

The group with the most modifiers matching will be selected.
If modifiers quantity is the same, order will be chosen based on modifier importance as listed above.

Example :

interface Test {
  optionalMethod?: () => {
      property: string;
    }
}

optionalMethod can be matched by the following groups, from most to least important:

'multiline-optional-method' or 'optional-multiline-method'.
'multiline-method'.
'optional-method'.
'method'.
'multiline-optional-member' or 'optional-multiline-member'.
'multiline-member'.
'optional-member'.
'member'.
'unknown'.

Example 2 (The most important group is written in the comments):

interface Interface {
  // 'index-signature'
  [key: string]: any;
  // 'optional-property'
  description?: string;
  // 'required-method'
  method(): string

Group with overridden settings

You may directly override options for a specific group by using an object with the group property and other option overrides.

type — Overrides the type option for that group.
order — Overrides the order option for that group.
fallbackSort — Overrides the fallbackSort option for that group.
sortBy — Overrides the sortBy option for that group.
newlinesInside — Overrides the newlinesInside option for that group.

{
  groups: [
    'method',
    { group: 'multiline-member', type: 'unsorted' }, // Elements from this group will not be sorted
  ]
}

Newlines between groups

You may place newlinesBetween objects between your groups to enforce the newline behavior between two specific groups.

See the newlinesBetween option.

This feature is only applicable when partitionByNewLine is false.

{
  newlinesBetween: 1,
  groups: [
    'a',
    { newlinesBetween: 0 }, // Overrides the global newlinesBetween option
    'b',
  ]
}

customGroups

Support for the object-based `customGroups` option is deprecated.

Migrating from the old to the current API is easy:

Old API:

{
  "key1": "value1",
  "key2": "value2"
}

Current API:

[
  {
    "groupName": "key1",
    "elementNamePattern": "value1"
  },
  {
    "groupName": "key2",
    "elementNamePattern": "value2"
  }
]

_{type: `Array`} _{default: `[]`}

Defines custom groups to match specific interface members.

A custom group definition may follow one of the two following interfaces:

interface CustomGroupDefinition {
  groupName: string
  type?: 'alphabetical' | 'natural' | 'line-length' | 'unsorted'
  order?: 'asc' | 'desc'
  fallbackSort?: { type: string; order?: 'asc' | 'desc'; sortBy?: 'name' | 'value' }
  sortBy?: 'name' | 'value'
  newlinesInside?: number | 'ignore'
  selector?: string
  modifiers?: string[]
  elementNamePattern?: string | string[] | { pattern: string; flags?: string } | { pattern: string; flags?: string }[]
  elementValuePattern?: string | string[] | { pattern: string; flags?: string } | { pattern: string; flags?: string }[]
}

An interface member will match a CustomGroupDefinition group if it matches all the filters of the custom group's definition.

or:

interface CustomGroupAnyOfDefinition {
  groupName: string
  type?: 'alphabetical' | 'natural' | 'line-length' | 'unsorted'
  order?: 'asc' | 'desc'
  fallbackSort?: { type: string; order?: 'asc' | 'desc'; sortBy?: 'name' | 'value' }
  sortBy?: 'name' | 'value'
  newlinesInside?: number | 'ignore'
  anyOf: Array<{
      selector?: string
      modifiers?: string[]
      elementNamePattern?: string | string[] | { pattern: string; flags?: string } | { pattern: string; flags?: string }[]
      elementValuePattern?: string | string[] | { pattern: string; flags?: string } | { pattern: string; flags?: string }[]
  }>
}

An interface member will match a CustomGroupAnyOfDefinition group if it matches all the filters of at least one of the anyOf items.

Attributes

groupName — The group's name, which needs to be put in the groups option.
selector — Filter on the selector of the element.
modifiers — Filter on the modifiers of the element. (All the modifiers of the element must be present in that list)
elementNamePattern — If entered, will check that the name of the element matches the pattern entered.
elementValuePattern — Only for properties. If entered, will check that the value of the property matches the pattern entered.
type — Overrides the type option for that custom group.
order — Overrides the order option for that custom group.
fallbackSort — Overrides the fallbackSort option for that custom group.
sortBy — Overrides the sortBy option for that custom group.
newlinesInside — Overrides the newlinesInside option for that group.

Match importance

The customGroups list is ordered: The first custom group definition that matches an element will be used.

Custom groups have a higher priority than any predefined group.

Example

Put all properties starting with id and name at the top, combine and sort metadata and optional multiline properties at the bottom. Anything else is put in the middle.

interface User {
  id: string                 // top
  name: string               // top
  age: number                // unknown
  isAdmin: boolean           // unknown
  lastUpdated_metadata: Date // bottom
  localization?: {            // optional-multiline-member
    // Stuff about localization
  }
  version_metadata: string   // bottom
}

groups and customGroups configuration:

 {
   groups: [
+    'top',                                  // [!code ++]
     'unknown',
+    ['optional-multiline-member', 'bottom'] // [!code ++]
   ],
+  customGroups: [                           // [!code ++]
+    {                                       // [!code ++]
+       groupName: 'top',                    // [!code ++]
+       selector: 'property',                // [!code ++]
+       elementNamePattern: '^(?:id|name)$', // [!code ++]
+    },                                      // [!code ++]
+    {                                       // [!code ++]
+       groupName: 'bottom',                 // [!code ++]
+       selector: 'property',                // [!code ++]
+       elementNamePattern: '.+_metadata$',  // [!code ++]
+    }                                       // [!code ++]
+  ]                                         // [!code ++]
 }

Usage

<CodeTabs code={[ { source: dedent` // eslint.config.js import perfectionist from 'eslint-plugin-perfectionist'

    export default [
      {
        plugins: {
          perfectionist,
        },
        rules: {
          'perfectionist/sort-interfaces': [
            'error',
            {
              type: 'alphabetical',
              order: 'asc',
              fallbackSort: { type: 'unsorted' },
              ignoreCase: true,
              specialCharacters: 'keep',
              sortBy: 'name',
              partitionByComment: false,
              partitionByNewLine: false,
              newlinesBetween: 'ignore',
              newlinesInside: 'ignore',
              useConfigurationIf: {},
              groups: [],
              customGroups: [],
            },
          ],
        },
      },
    ]
  `,
  name: 'Flat Config',
  value: 'flat',
},
{
  source: dedent`
    // .eslintrc.js
    module.exports = {
      plugins: [
        'perfectionist',
      ],
      rules: {
        'perfectionist/sort-interfaces': [
          'error',
          {
            type: 'alphabetical',
            order: 'asc',
            fallbackSort: { type: 'unsorted' },
            ignoreCase: true,
            specialCharacters: 'keep',
            sortBy: 'name',
            partitionByComment: false,
            partitionByNewLine: false,
            newlinesBetween: 'ignore',
            newlinesInside: 'ignore',
            useConfigurationIf: {},
            groups: [],
            customGroups: [],
          },
        ],
      },
    }
  `,
  name: 'Legacy Config',
  value: 'legacy',
},

]} type="config-type" client:load lang="tsx" />

Version

This rule was introduced in v0.1.0.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Try it out

Options

type

order

fallbackSort

alphabet

ignoreCase

specialCharacters

locales

sortBy

partitionByComment

partitionByNewLine

newlinesBetween

newlinesInside

useConfigurationIf

groups

Example

Index-signatures

Methods

Properties

Scope of the `required` modifier

Important notes

The `unknown` group

Behavior when multiple groups match an element

Group with overridden settings

Newlines between groups

customGroups

Attributes

Match importance

Example

Usage

Version

Resources

FilesExpand file tree

sort-interfaces.mdx

Latest commit

History

sort-interfaces.mdx

File metadata and controls

Try it out

Options

type

order

fallbackSort

alphabet

ignoreCase

specialCharacters

locales

sortBy

partitionByComment

partitionByNewLine

newlinesBetween

newlinesInside

useConfigurationIf

groups

Example

Index-signatures

Methods

Properties

Scope of the required modifier

Important notes

The unknown group

Behavior when multiple groups match an element

Group with overridden settings

Newlines between groups

customGroups

Attributes

Match importance

Example

Usage

Version

Resources

Scope of the `required` modifier

The `unknown` group