noDuplicateClassMembers

Diagnostic Category: lint/suspicious/noDuplicateClassMembers

JavaScript (and super languages)

Since: v1.0.0

Sources:

Same as: no-dupe-class-members
Same as: @typescript-eslint/no-dupe-class-members

Description

Disallow duplicate class members.

If there are declarations of the same name among class members, the last declaration overwrites other declarations silently. It can cause unexpected behaviours.

Examples

Invalid

class Foo {
  bar() { }
  bar() { }
}

code-block.js:3:3 lint/suspicious/noDuplicateClassMembers ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Duplicate class member name “bar”
  
    1 │ class Foo {
    2 │   bar() { }
  > 3 │   bar() { }
      │   ^^^^^^^^^
    4 │ }
    5 │

class Foo {
  bar() { }
  get bar() { }
}

code-block.js:3:3 lint/suspicious/noDuplicateClassMembers ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Duplicate class member name “bar”
  
    1 │ class Foo {
    2 │   bar() { }
  > 3 │   get bar() { }
      │   ^^^^^^^^^^^^^
    4 │ }
    5 │

class Foo {
  bar;
  bar() { }
}

code-block.js:3:3 lint/suspicious/noDuplicateClassMembers ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Duplicate class member name “bar”
  
    1 │ class Foo {
    2 │   bar;
  > 3 │   bar() { }
      │   ^^^^^^^^^
    4 │ }
    5 │

class Foo {
  static bar() { }
  static bar() { }
}

code-block.js:3:3 lint/suspicious/noDuplicateClassMembers ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Duplicate class member name “bar”
  
    1 │ class Foo {
    2 │   static bar() { }
  > 3 │   static bar() { }
      │   ^^^^^^^^^^^^^^^^
    4 │ }
    5 │

Valid

class Foo {
  bar() { }
  qux() { }
}

class Foo {
  set bar(value) { }
  get bar() { }
}

class Foo {
  bar;
  qux;
}

class Foo {
  bar;
  qux() { }
}

class Foo {
  static bar() { }
  bar() { }
}

How to configure

{
  "linter": {
    "rules": {
      "suspicious": {
        "noDuplicateClassMembers": "error"
      }
    }
  }
}