Avoid duplicate class members

このページは日本語には対応しておりません。随時翻訳に取り組んでいます。
翻訳に関してご質問やご意見ございましたら、お気軽にご連絡ください

Metadata

ID: javascript-best-practices/no-dupe-class-members

Language: JavaScript

Severity: Error

Category: Best Practices

Description

JavaScript allows multiple class members with the same identifier, and the last duplicate class member takes precedence over previous declarations, which is undesired behavior. Disallow duplicate class members.

Non-Compliant Code Examples

class A { foo() {} foo() {} }
!class A { foo() {} foo() {} };
class A { 'foo'() {} 'foo'() {} }
class A { 10() {} 1e1() {} }
class A { ['foo']() {} ['foo']() {} }
class A { static ['foo']() {} static foo() {} }
class A { set 'foo'(value) {} set ['foo'](val) {} }
class A { ''() {} ['']() {} }
class A { [`foo`]() {} [`foo`]() {} }
class A { static get [`foo`]() {} static get ['foo']() {} }
class A { foo() {} [`foo`]() {} }
class A { get [`foo`]() {} 'foo'() {} }
class A { static 'foo'() {} static [`foo`]() {} }
class A { ['constructor']() {} ['constructor']() {} }
class A { static [`constructor`]() {} static constructor() {} }
class A { static constructor() {} static 'constructor'() {} }
class A { [123]() {} [123]() {} }
class A { [0x10]() {} 16() {} }
class A { [100]() {} [1e2]() {} }
class A { [123.00]() {} [`123`]() {} }
class A { static '65'() {} static [0o101]() {} }
class A { [123n]() {} 123() {} }
class A { [null]() {} 'null'() {} }
class A { foo() {} foo() {} foo() {} }
class A { static foo() {} static foo() {} }
class A { foo() {} get foo() {} }
class A { set foo(value) {} foo() {} }
class A { foo; foo; }

Compliant Code Examples

class A { foo() {} bar() {} }
class A { static foo() {} foo() {} }
class A { get foo() {} set foo(value) {} }
class A { static foo() {} get foo() {} set foo(value) {} }
class A { foo() { } } class B { foo() { } }
class A { [foo]() {} foo() {} }
class A { 'foo'() {} 'bar'() {} baz() {} }
class A { *'foo'() {} *'bar'() {} *baz() {} }
class A { get 'foo'() {} get 'bar'() {} get baz() {} }
class A { 1() {} 2() {} }
class A { ['foo']() {} ['bar']() {} }
class A { [`foo`]() {} [`bar`]() {} }
class A { [12]() {} [123]() {} }
class A { [1.0]() {} ['1.0']() {} }
class A { [0x1]() {} [`0x1`]() {} }
class A { [null]() {} ['']() {} }
class A { get ['foo']() {} set ['foo'](value) {} }
class A { ['foo']() {} static ['foo']() {} }

// computed "constructor" key doesn't create constructor
class A { ['constructor']() {} constructor() {} }
class A { 'constructor'() {} [`constructor`]() {} }
class A { constructor() {} get [`constructor`]() {} }
class A { 'constructor'() {} set ['constructor'](value) {} }

// not assumed to be statically-known values
class A { ['foo' + '']() {} ['foo']() {} }
class A { [`foo${''}`]() {} [`foo`]() {} }
class A { [-1]() {} ['-1']() {} }

// private and public
class A { foo; static foo; }
class A { foo; #foo; }
class A { '#foo'; #foo; }
https://static.datadoghq.com/static/images/logos/github_avatar.svg https://static.datadoghq.com/static/images/logos/vscode_avatar.svg jetbrains

Seamless integrations. Try Datadog Code Analysis