Typescript weirdness:
export type MyType = 0 | 1 | 2;
This works. But this does not:
export const ONE = 1;
export const TWO = 2;
export const THREE = 3;
export type MyType = ONE | TWO | THREE;
With the second example you are in typespace using a value (the declared consts) to declare a type. you need to use typeof ONE TWO or THREE. In the first example, 1 2 and 3 count as types themselves.
The problem is that you are defining MyType as a type and there you're referencing a variable. So what you need to actually do to match types with types is to request the type of your value. You can do that by using the typeof operator like:
export const ONE = 1;
export const TWO = 2;
export const THREE = 3;
export type MyType = typeof ONE | typeof TWO | typeof THREE;
First of all you should use typeof, like mentioned in previous answer.
Second, if I understand correctly, you want to create type containing excatly these 3 given values. To do this, you need to use as const keywords.
For example:
export const A = 1 as const;
export const B = 2 as const;
export type MyType = typeof A | typeof B;
and more usefull example for const variable:
export const status = {
FIRST: 1,
SECOND: 2
} as const;
export type StatusType = typeof status[keyof typeof status];
export interface IEntity {
id: number;
status: StatusType;
}
// You can use it elsewhere like this:
const A: IEntity = {
id: 1,
type: status.FIRST
};