Typescript class getters are not returning any data

January 28, 2023

I am trying to create a Typescript class that has read-only properties based on other properties in the class. The properties in question are the firstLastName and lastFirstName properties. Here is my class:

export interface IMember {
  id: string;
  firstName: string;
  lastName: string;
  active: boolean;
  readonly firstLastName: string;
  readonly lastFirstName: string;
}

export class Member implements IMember {
  id: string;
  firstName: string;
  lastName: string;
  active: boolean;
  get firstLastName(): string {
    return `${this.firstName} ${this.lastName}`;
  }
  get lastFirstName(): string {
    return `${this.lastName}, ${this.firstName}`;
  }
}

I have tried manually creating a new member object and assigning the four required properties, and I also tried creating member objects from JSON. In both cases, the code acts like the firstLastName and lastFirstName properties aren’t there at all. Also, when creating the object manually, I have to mark the type as Partial, or the compiler complains that the object is missing properties (firstLastName and lastFirstName). This seems so straightforward, and I found another question here that basically showed exactly what I’m doing as the solution, but it’s just not working for me.

>Solution :

Mb You have to initialize properties.
This code works in the playground:

interface IMember {
  id: string;
  firstName: string;
  lastName: string;
  active: boolean;
  readonly firstLastName: string;
  readonly lastFirstName: string;
}

class Member implements IMember {
  id: string = "";
  firstName: string = "first";
  lastName: string = "last";
  active: boolean = false;
  get firstLastName(): string {
    return `${this.firstName} ${this.lastName}`;
  }
  get lastFirstName(): string {
    return `${this.lastName}, ${this.firstName}`;
  }
}

const m = new Member

console.log(m.firstLastName)