I'm trying to create a type to describe an ES6 Proxy object where I will know the types for a few keys, and the rest of the keys will be generic with a callback as a value and I won't know their names until runtime.
However, if I try something like this:
interface MyCallback {
(): void;
}
interface MyType {
myKey1: number;
[key: string]: MyCallBack;
}
I get errors like:
[ts] Property 'myKey1' of type 'number' is not assignable to string index type 'MyCallback'.
If I add [key: string]: number, I get the error Duplicate string index signature.
If I overload it so it's like number | MyCallback, I get this error if I try to call a callback on a MyType instance:
[ts] Cannot invoke an expression whose type lacks a call signature. Type 'number | MyCallback' has no compatible call signatures.
Is it possible to have a type like I'm trying to create in TypeScript?
the answer is sort of. You can accomplish this with intersection types:
interface MyType {
myKey1: number;
}
interface MyCallBack {
(): void;
}
interface GenericCallbackType {
[key: string]: MyCallBack;
}
type CombinedType = MyType & GenericCallbackType;
const obj: CombinedType = {
myKey1: 8,
anyString: () => {}
}
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