typescript interface definition with an unknown property key

Question

How to express an interface (IResponse), with one property has a string key (which is not known statically). Below, the key values can be anything like bo

Answer 1

If you define one interface for the known types and a separate one for the "unknown" types, you could use a type assertion to tell the compiler the one you wanted to use.

It isn't ideal, but you are working in a edge case (i.e. not entirely dynamic, not entirely static).

export interface IMeta{}
export interface IValue{}
export interface IFunkyResponse {
     [index: string]:IValue[];
}
export interface IResponse {
     meta: IMeta;
}

export class Response implements IResponse {
    meta:IMeta;
    values:IValue[];
    books:IValue[];
    anything:IValue[];
}

You can type-assert between resp and resp to access one or the other of the styles.