My definition includes type A and type B
type A = {
kind: "A",
value: string,
value2: string,
value3: string,
};
type B = { kind: "B" } & A ;
I am aiming for type B to have all the characteristics of type A but with a distinct kind value
However, when I attempt the following:
const temp: B = {
kind: "B",
value: "X",
value2: "X2",
value3: "X3",
};
The following error is triggered:
TS2322 type
stringis not assignable to typenever
This is because an object cannot simultaneously have type "A" and "B".
Here are a couple of ways to correct this issue:
1. Using Generics:
type WithKind<T extends string> = {
kind: T,
value: string,
value2: string,
value3: string,
}
type A = WithKind<"A">;
type B = WithKind<"B">;
2. Omitting Fields:
type B = Omit<A, "kind"> & { kind: "B" } ;
The root of your issue lies in the fact that
"A" & "B" === never
If you wish to replace a hardcoded string value with a new one, you can first Omit it.
type B = { kind: "B" } & Omit<A, "kind">;
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