13af6ab5fSopenharmony_ci# ``in`` operator is not supported 23af6ab5fSopenharmony_ci 33af6ab5fSopenharmony_ciRule ``arkts-no-in`` 43af6ab5fSopenharmony_ci 53af6ab5fSopenharmony_ci**Severity: error** 63af6ab5fSopenharmony_ci 73af6ab5fSopenharmony_ciArkTS does not support the operator ``in``. However, this operator makes 83af6ab5fSopenharmony_cilittle sense since the object layout is known at compile time, and cannot 93af6ab5fSopenharmony_cibe modified at runtime. Use ``instanceof`` as a workaround if you still need 103af6ab5fSopenharmony_cito check whether certain class members exist. 113af6ab5fSopenharmony_ci 123af6ab5fSopenharmony_ci 133af6ab5fSopenharmony_ci## TypeScript 143af6ab5fSopenharmony_ci 153af6ab5fSopenharmony_ci 163af6ab5fSopenharmony_ci``` 173af6ab5fSopenharmony_ci 183af6ab5fSopenharmony_ci class Person { 193af6ab5fSopenharmony_ci name: string = "" 203af6ab5fSopenharmony_ci } 213af6ab5fSopenharmony_ci let p = new Person() 223af6ab5fSopenharmony_ci 233af6ab5fSopenharmony_ci let b = "name" in p // true 243af6ab5fSopenharmony_ci 253af6ab5fSopenharmony_ci``` 263af6ab5fSopenharmony_ci 273af6ab5fSopenharmony_ci## ArkTS 283af6ab5fSopenharmony_ci 293af6ab5fSopenharmony_ci 303af6ab5fSopenharmony_ci``` 313af6ab5fSopenharmony_ci 323af6ab5fSopenharmony_ci class Person { 333af6ab5fSopenharmony_ci name: string = "" 343af6ab5fSopenharmony_ci } 353af6ab5fSopenharmony_ci let p = new Person() 363af6ab5fSopenharmony_ci 373af6ab5fSopenharmony_ci let b = p instanceof Person // true, and "name" is guaranteed to be present 383af6ab5fSopenharmony_ci 393af6ab5fSopenharmony_ci``` 403af6ab5fSopenharmony_ci 413af6ab5fSopenharmony_ci## See also 423af6ab5fSopenharmony_ci 433af6ab5fSopenharmony_ci- Recipe 001: Objects with property names that are not identifiers are not supported (``arkts-identifiers-as-prop-names``) 443af6ab5fSopenharmony_ci- Recipe 002: ``Symbol()`` API is not supported (``arkts-no-symbol``) 453af6ab5fSopenharmony_ci- Recipe 029: Indexed access is not supported for fields (``arkts-no-props-by-index``) 463af6ab5fSopenharmony_ci- Recipe 059: ``delete`` operator is not supported (``arkts-no-delete``) 473af6ab5fSopenharmony_ci- Recipe 060: ``typeof`` operator is allowed only in expression contexts (``arkts-no-type-query``) 483af6ab5fSopenharmony_ci- Recipe 144: Usage of standard library is restricted (``arkts-limited-stdlib``) 493af6ab5fSopenharmony_ci 503af6ab5fSopenharmony_ci 51