Can't have a regular property and computed property keys in the same interface

Question

TypeScript version: 3.6.4

In my state, I want to have both a computed property and a regular property key inside an interface but TypeScript is having trouble parsing that. Before creating a GitHub issue on the repository, I just want to make sure I'm not doing something wrong and wasting the devs' time.

type Stat = 'hp' | 'attack' | 'defense' | 'speed';

interface State {
    [x in Stat]: number;
    type: string
}

I thought that would work but then TypeScript highlights type and says '}' expected. ts(1005) '}' expected. ts(1005) . If I put type at the top, it highlights [x in Stat] and says A computed property name must be of type 'string', 'number', 'symbol', or 'any'. ts(2464) A computed property name must be of type 'string', 'number', 'symbol', or 'any'. ts(2464) & 'Stat' only refers to a type, but is being used as a value here.ts(2693) . If i comment out one of the 2 lines, TypeScript is totally okay with it.

Am I doing something wrong here or is this just not possible?

Answer 1

Without a better understanding of what you are working on, my proposal may be off target.

You can probably work out something from mapped types and intersection:

/** Refefernce interface */
interface IStat {
  attack: unknown;
  defense: unknown;
  hp: unknown;
  speed: unknown;
}

/** (optional) `keyof` reference interface */
type Stat = keyof IStat

/** Mapped IStat properties intersected with `type` */
type State = {
  [K in keyof IStat]?: number; // change `number` with IStat[K] if you want the types from IStat;
} & { type: string; };

Here is a Typescript Playground for you to experiment further this approach.

Answer 2

is this what you want?

type Stat = 'hp' | 'attack' | 'defense' | 'speed';

type State = Record <Stat, number> & {
  type: string;
}

const s: State = {
  hp: 100,
  attack: 12,
  defense: 12,
  speed: 3,
  type: "myType"
}