# Declaring fields in ``constructor`` is not supported Rule ``arkts-no-ctor-prop-decls`` **Severity: error** ArkTS does not support declaring class fields in the ``constructor``. Declare class fields inside the ``class`` declaration instead. ## TypeScript ``` class Person { constructor( protected ssn: string, private firstName: string, private lastName: string ) { this.ssn = ssn this.firstName = firstName this.lastName = lastName } getFullName(): string { return this.firstName + " " + this.lastName } } ``` ## ArkTS ``` class Person { protected ssn: string private firstName: string private lastName: string constructor(ssn: string, firstName: string, lastName: string) { this.ssn = ssn this.firstName = firstName this.lastName = lastName } getFullName(): string { return this.firstName + " " + this.lastName } } ```