I have this response type
export interface IResponse {
status: boolean;
message: string;
}
Then I would like to pass a custom interface to this type.
const res: IResponse<{count: number}> = await ...
How to modify my type so that res.count is recognized?
You can declare a new generic type as an alias of an intersection type:
type CustomResponse<T> = IResponse & T
export function test() {
const res: CustomResponse<{count: number}> = { }
console.log(res.status) // true
console.log(res.count) // 1
}
Note that this approach will "lock" the type, as then CustomResponse is not an interface anymore and therefore can't be extended.
// Compile error
export interface A extends CustomType<string> {
}
I'm not sure I understand what you want to do exactly, but if you want to extend an interface you can do it like so:
interface ExtendedResponse extends IResponse {
count: number
}
Then you can use it as you would any other interface:
const res: ExtendedResponse = await ...
One option would be:
const res: IResponse<IResponse & {count: number}> = await ...
the second one @Hoff stated. You need to extend IResponse with your custom one
Although I think it would be better for you do do something like:
export interface IResponse {
status: boolean;
message: string;
}
export type TResponse<T> = IResponse & T;
export interface Count {
count: number
}
const res: IResponse<Count> = await ...
