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eslint/class-methods-use-this Restriction

What it does

Enforce that class methods utilize this.

Why is this bad?

For class methods that do not use this, you should consider converting them to static methods. This is not always possible or desirable, but it can help clarify that the method does not rely on instance state.

If you do convert the method into a static function, instances of the class that call that particular method have to be converted to a static call as well.

Examples

Examples of incorrect code for this rule:

js
class A {
  foo() {
    console.log("Hello World");
  }
}

Examples of correct code for this rule:

js
class A {
  foo() {
    this.bar = "Hello World"; // OK, this is used
  }
}

class B {
  constructor() {
    // OK. constructor is exempt
  }
}

class C {
  static foo() {
    // OK. static methods aren't expected to use this.
  }
}

Configuration

This rule accepts a configuration object with the following properties:

enforceForClassFields

type: boolean

default: true

Enforce this rule for class fields that are functions.

exceptMethods

type: array

default: []

List of method names to exempt from this rule.

exceptMethods[n]

type: object

exceptMethods[n].name

type: string

exceptMethods[n].private

type: boolean

ignoreClassesWithImplements

type: "all" | "public-fields"

default: null

Whether to ignore classes that implement interfaces.

ignoreOverrideMethods

type: boolean

default: false

Whether to ignore methods that are overridden.

How to use

To enable this rule using the config file or in the CLI, you can use:

json
{
  "rules": {
    "class-methods-use-this": "error"
  }
}
bash
oxlint --deny class-methods-use-this

References