Typescript extend interface as optional

Question

I have two interfaces:

interface ISuccessResponse {
    Success: boolean;
    Message: string;
}

and

interface IAppVersion extends ISuccessResponse {
    OSVersionStatus: number;
    LatestVersion: string;
}

I would like to extend the ISuccessResponse interface as optional; I can do this, how to overwrite it, but is there another option?

interface IAppVersion {
    OSVersionStatus: number;
    LatestVersion: string;
    Success?: boolean;
    Message?: string;
}

I do not want to do this.

Answer 1

If you want to Success, and Messagehave been optional, you can do this:

interface IAppVersion {
    OSVersionStatus: number;
    LatestVersion: string;
    Success?: boolean;
    Message?: string;
}

You cannot use the keyword extendsto connect the interface ISuccessResponse, but then change the contract defined in this interface (this interface says that they are necessary). p>

Answer 2

, Typescript 2.1 Partial<T> , :

interface ISuccessResponse {
    Success: boolean;
    Message: string;
}

interface IAppVersion extends Partial<ISuccessResponse> {
    OSVersionStatus: number;
    LatestVersion: string;
}

declare const version: IAppVersion;
version.Message // Type is string | undefined

Answer 3

:

interface ISuccessResponse {
    Success?: boolean;
    Message?: string;
}
interface IAppVersion extends ISuccessResponse {
    OSVersionStatus: number;
    LatestVersion: string;
}
class MyTestClass implements IAppVersion {
    LatestVersion: string;
    OSVersionStatus: number;
}