13af6ab5fSopenharmony_ci# Declaring fields in ``constructor`` is not supported 23af6ab5fSopenharmony_ci 33af6ab5fSopenharmony_ciRule ``arkts-no-ctor-prop-decls`` 43af6ab5fSopenharmony_ci 53af6ab5fSopenharmony_ci**Severity: error** 63af6ab5fSopenharmony_ci 73af6ab5fSopenharmony_ciArkTS does not support declaring class fields in the ``constructor``. 83af6ab5fSopenharmony_ciDeclare class fields inside the ``class`` declaration instead. 93af6ab5fSopenharmony_ci 103af6ab5fSopenharmony_ci 113af6ab5fSopenharmony_ci## TypeScript 123af6ab5fSopenharmony_ci 133af6ab5fSopenharmony_ci 143af6ab5fSopenharmony_ci``` 153af6ab5fSopenharmony_ci 163af6ab5fSopenharmony_ci class Person { 173af6ab5fSopenharmony_ci constructor( 183af6ab5fSopenharmony_ci protected ssn: string, 193af6ab5fSopenharmony_ci private firstName: string, 203af6ab5fSopenharmony_ci private lastName: string 213af6ab5fSopenharmony_ci ) { 223af6ab5fSopenharmony_ci this.ssn = ssn 233af6ab5fSopenharmony_ci this.firstName = firstName 243af6ab5fSopenharmony_ci this.lastName = lastName 253af6ab5fSopenharmony_ci } 263af6ab5fSopenharmony_ci 273af6ab5fSopenharmony_ci getFullName(): string { 283af6ab5fSopenharmony_ci return this.firstName + " " + this.lastName 293af6ab5fSopenharmony_ci } 303af6ab5fSopenharmony_ci } 313af6ab5fSopenharmony_ci 323af6ab5fSopenharmony_ci``` 333af6ab5fSopenharmony_ci 343af6ab5fSopenharmony_ci## ArkTS 353af6ab5fSopenharmony_ci 363af6ab5fSopenharmony_ci 373af6ab5fSopenharmony_ci``` 383af6ab5fSopenharmony_ci 393af6ab5fSopenharmony_ci class Person { 403af6ab5fSopenharmony_ci protected ssn: string 413af6ab5fSopenharmony_ci private firstName: string 423af6ab5fSopenharmony_ci private lastName: string 433af6ab5fSopenharmony_ci 443af6ab5fSopenharmony_ci constructor(ssn: string, firstName: string, lastName: string) { 453af6ab5fSopenharmony_ci this.ssn = ssn 463af6ab5fSopenharmony_ci this.firstName = firstName 473af6ab5fSopenharmony_ci this.lastName = lastName 483af6ab5fSopenharmony_ci } 493af6ab5fSopenharmony_ci 503af6ab5fSopenharmony_ci getFullName(): string { 513af6ab5fSopenharmony_ci return this.firstName + " " + this.lastName 523af6ab5fSopenharmony_ci } 533af6ab5fSopenharmony_ci } 543af6ab5fSopenharmony_ci 553af6ab5fSopenharmony_ci``` 563af6ab5fSopenharmony_ci 573af6ab5fSopenharmony_ci 58