Perfectionist

sort-classes

Enforce sorted class members.

Organizing class members in a consistent order improves both readability and maintainability.

This rule helps developers quickly locate class members and understand the overall structure of the class.

By sorting class members systematically, confusion is minimized, and the code becomes more intuitive to navigate. This practice not only aids in individual productivity but also enhances team collaboration by establishing clear and predictable coding standards.

Try it out

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 the length of the code line (shorter lines first).
  • 'custom' — Sort items using the alphabet entered in the alphabet option.

order

default: 'asc'

Determines whether the sorted items should be 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).

alphabet

default: ''

Only used when the type option is set to 'custom'. Specifies the custom alphabet to use when sorting.

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

Example: 0123456789abcdef...

ignoreCase

default: true

Controls whether sorting should be case-sensitive or not.

  • 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

Controls whether special characters should be trimmed, removed or kept 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. See 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.

partitionByComment

default: false

Allows you to use comments to separate the class members into logical groups. This can help in organizing and maintaining large classes by creating partitions within the class based on comments.

  • true — All comments will be treated as delimiters, creating partitions.
  • false — Comments will not be used as delimiters.
  • string — A regexp pattern to specify which comments should act as delimiters.

partitionByNewLine

default: false

When true, the rule will not sort the members of a class if there is an empty line between them. This can be useful for keeping logically separated groups of members in their defined order.

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

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

  // Group 3
  address: {
    street: string;
    city: string;
  };
  phone?: string;

  // Group 4
  updateAddress(address: string) {}
  updatePhone(phone?: string) {}

  // Group 5
  editFirstName(firstName: string) {}
  editLastName(lastName: string) {}
};

newlinesBetween

default: 'ignore'

Specifies how new lines should be handled between class member groups.

  • ignore — Do not report errors related to new lines between object type groups.
  • always — Enforce one new line between each group, and forbid new lines inside a group.
  • never — No new lines are allowed in object types.

This options is only applicable when partitionByNewLine is false.

ignoreCallbackDependenciesPatterns

default: []

Allows you to specify regexp patterns of function names that should ignore dependency sorting in their callback functions.

Example with ignoreCallbackDependenciesPatterns: ['^computed$']:

class User {
  fullName = computed(() => this.role + ' - ' + this.username);
  role = signal('admin');
  username = signal('John');
};

Without ignoreCallbackDependenciesPatterns: ['^computed$'], role and username would be sorted before fullName as it depends on them.

groups

type: Array<string | string[]>

default:

[
  'index-signature',
  'static-property',
  'static-block',
  ['protected-property', 'protected-accessor-property'],
  ['private-property', 'private-accessor-property'],
  ['property', 'accessor-property'],
  'constructor',
  'static-method',
  'protected-method',
  'private-method',
  'method',
  ['get-method', 'set-method'],
  'unknown',
]

Allows you to specify a list of class member groups for sorting. Groups help organize class members into categories, prioritizing them during sorting.

Each class 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.

Constructors

  • Selector: constructor.
  • Modifiers: protected, private, public.
  • Example: protected-constructor, private-constructor, public-constructor or constructor.

Methods

  • Selectors: get-method, set-method, method.
  • Modifiers: static, abstract, decorated, override, protected, private, public, optional, async.
  • Example: private-static-accessor-property, protected-abstract-override-method or static-get-method.

The optional modifier is incompatible with the get-method and set-method selectors.

The abstract modifier is incompatible with the static, private and decorated modifiers.

constructor, get-method and set-method elements will also be matched as method.

Accessors

  • Selector: accessor-property.
  • Modifiers: static, abstract, decorated, override, protected, private, public.
  • Example: private-static-accessor-property, protected-abstract-override-method or static-get-method.

The abstract modifier is incompatible with the static, private and decorated modifiers.

Properties

  • Selectors: function-property, property.
  • Modifiers: static, declare, abstract, decorated, override, readonly, protected, private, public, optional, async.
  • Example: readonly-decorated-property.

The abstract modifier is incompatible with the static, private and decorated modifiers.

The declare modifier is incompatible with the override and decorated modifiers.

The function-property selector will match properties whose values are defined functions or arrow-functions. As such, the declare and abstract modifiers are incompatible with this selector.

The async modifier is reserved for the function-property selector.

Index-signatures

  • Selector: index-signature.
  • Modifiers: static, readonly.
  • Example: static-readonly-index-signature.

Static-blocks

  • Selector: static-block.
  • Modifiers: No modifier available.
  • Example: static-block.

Important notes

Scope of the private modifier

The private modifier will currently match any of the following:

  • Elements with the private keyword.
  • Elements with their name starting with #.
Scope of the public modifier

Elements that are not protected nor private will be matched with the public modifier, even if the keyword is not present.

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, the members will remain in their original order.

Behavior when multiple groups match an element

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

  1. Selector priority: constructor, get-method and set-method groups will always take precedence over method groups.
  2. If the selector is the same, the group with the most modifiers matching will be selected.
  3. If modifiers quantity is the same, order will be chosen based on modifier importance as listed above.

Example 1:

abstract class Class {

    protected abstract get field();

}

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

  • abstract-protected-get-method or protected-abstract-get-method.
  • abstract-get-method.
  • protected-get-method.
  • get-method.
  • abstract-protected-method or protected-abstract-method.
  • abstract-method.
  • protected-method.
  • method.
  • unknown.

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

abstract class Example extends BaseExample {

  // 'index-signature'
  [key: string]: any;

  // 'public-static-property'
  static instance: Example;

  // 'declare-protected-static-readonly-property'
  declare protected static readonly value: string;

  // 'static-block'
  static {
    console.log("I am a static block");
  }

  // 'public-property'
  public description: string;

  // 'public-decorated-property'
  @SomeDecorator
  public value: number;

  // 'public-decorated-accessor-property'
  @SomeDecorator
  public accessor value: number;

  // 'public-decorated-get-method'
  @SomeDecorator
  get decoratedValue() {
    return this._value;
  }

  // 'public-decorated-set-method'
  @SomeDecorator
  set decoratedValue(value: number) {
    this._value = value;
  }

  // 'public-decorated-get-method'
  @SomeDecorator
  get value() {
    return this._value;
  }

  // 'public-get-method'
  get value() {
    return this._value;
  }

  // 'public-set-method'
  set value(value: number) {
    this._value = value;
  }

  // 'protected-abstract-override-readonly-decorated-property'
  @SomeDecorator
  protected abstract override readonly _value: number;

  // 'protected-decorated-accessor-property'
  @SomeDecorator
  protected accessor _value: number;

  // 'protected-property'
  protected name: string;

  // 'protected-decorated-get-method'
  @SomeDecorator
  protected get value() {
    return this._value;
  }

  // 'private-decorated-property'
  @SomeDecorator
  private _value: number;

  // 'private-decorated-accessor-property'
  @SomeDecorator
  private accessor _value: number;

  // 'private-property'
  private name: string;

  // 'private-decorated-get-method'
  @SomeDecorator
  private get value() {
    return this._value;
  }

  // 'public-constructor'
  constructor(value: number) {
    this._value = value;
  }

  // 'public-static-method'
  static getInstance() {
    return this.instance;
  }

  // 'protected-static-method'
  protected static initialize() {
    this.instance = new Example(0);
  }

  // 'private-static-method'
  private static initialize() {
    this.instance = new Example(0);
  }

  // 'public-decorated-method'
  @SomeDecorator
  public decoratedMethod() {
    return this._value;
  }

  // 'public-method'
  public display() {
    console.log(this._value);
  }

  // 'protected-method'
  protected calculate() {
    return this._value * 2;
  }

  // private-function-property
  private arrowProperty = () => {};

  // 'private-method'
  private calculate() {
    return this._value * 2;
  }

  // private-function-property
  private functionProperty = function() {};
}

customGroups

Migrating from the old API

Support for the object-based customGroups option has been removed.

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<CustomGroupDefinition | CustomGroupAnyOfDefinition>

default: []

You can define your own groups and use regex for matching very specific class 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'
  selector?: string
  modifiers?: string[]
  elementNamePattern?: string
  elementValuePattern?: string
  decoratorNamePattern?: string
}

A class 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'
  anyOf: Array<{
      selector?: string
      modifiers?: string[]
      elementNamePattern?: string
      elementValuePattern?: string
      decoratorNamePattern?: string
  }>
}

A class 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 non-function properties. If entered, will check that the value of the property matches the pattern entered.
  • decoratorNamePattern: If entered, will check that at least one decorator matches the pattern entered.
  • type: Overrides the sort type for that custom group. unsorted will not sort the group.
  • order: Overrides the sort order for that custom 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. If you want a predefined group to take precedence over a custom group, you must write a custom group definition that does the same as what the predefined group does (using selector and modifiers filters), and put it first in the list.

Example:

 {
   groups: [
    'static-block',
    'index-signature',
+   'input-properties',
+   'output-properties',
    'constructor',
+   'unsorted-methods-and-other-properties',
    ['get-method', 'set-method'],
    'unknown',
   ],
+  customGroups: [                                          
+    {                                                      
+      // `constructor()` members must not match
+      // `unsorted-methods-and-other-properties`
+      // so make them match this first
+       groupName: 'constructor',
+       selector: 'constructor',
+    },
+    {                                                      
+       groupName: 'input-properties',
+       selector: 'property',
+       modifiers: ['decorated'],
+       decoratorNamePattern: 'Input',
+    },
+    {                                                      
+       groupName: 'output-properties',
+       selector: 'property',
+       modifiers: ['decorated'],
+       decoratorNamePattern: 'Output',
+    },
+    {                                                      
+       groupName: 'unsorted-methods-and-other-properties',
+       type: 'unsorted',
+       anyOf: [                                            
+         {                                                 
+            selector: 'method',
+         },
+         {                                                 
+            selector: 'property',
+         },
+       ]                                                   
+    },
+  ]                                                        
 }

Usage

Version

This rule was introduced in v0.11.0.

Resources

Table of Contents