Is it necessary to use 'readonly' keyword during service initialization in constructor?

Question

In Angular 2+ combined with Type Script is it necessary to use readonly keyword when we initialize services in the component constructor?

What is the purpose to do so?

export class MyComponent {

    constructor(private readonly http: HttpClient) {}

}

Answer 1

It is not required, however it is good practice since you probably don't want to reassign to the http property later on.

See the Typescript doc for more details:

Read-only properties may have initializers and may be assigned to in constructors within the same class declaration, but otherwise assignments to read-only properties are disallowed.

Answer 2

No, it's not necessary to use the readonly keyword such usage is not mentioned in angular docs and not used in practice