Can an array containing
[Observable<string>, Observable<number>][string, number] using generics?
function example(obs: Observable<any>[]): any[] { }
Intended Outcome:
example(of(''), of(0)) // should return [string, number];
I am aware that rxjs uses ObservedValueOf<O> and function overloading for combineLatest, but I prefer not to use the same approach for overloading.
It might be a good idea to update the call signature for example() using a mapped type applied to an array:
declare function example<T extends any[]>
(...obs: { [K in keyof T]: Observable<T[K]> }): T;
In this case, the type T corresponds to the output array/tuple type, and the input parameter obs maps T so that each element is encapsulated within Observable<>. Thanks to inference from mapped types, T can automatically be deduced from the type of obs when you invoke example():
const result = example(of(''), of(0));
// const result: [string, number]
This should give you the desired type.
Keep in mind that although the question doesn't specifically address the implementation details, there may be potential issues down the line. While I'm no rxjs expert, it appears that converting an Observable<X> to an X synchronously could pose challenges because the observable might not have a value of type
X</code available immediately upon calling <code>example()example() throw an error if the inputs lack ready values. Alternatively, it might make more sense for example() to transform [Observable<string>, Observable<number>]Observable<[string, number]>One effective approach is to combine functions that work with arrays of Observables, such as combineLatest or forkJoin, along with the toPromise method of Observable and async/await syntax. Here's a sample code snippet:
async function customExample<A, B>(observables: [obs1: Observable<A>, obs2: Observable<B>]) {
return combineLatest(observables).toPromise()
}
const observable1 = of('')
const observable2 = of(1)
async function runTest() {
const result = await customExample([observable1, observable2])
}
In this example, the variable result would have the type [string, number].
It's important to note that transforming Observables (which are continuous streams) into Promises is generally not recommended.
Observables are designed to be subscribed to, where you provide up to three functions - one for handling emissions (next), one for error handling (error), and one for completion handling (complete). This is the recommended way to use Observables effectively.
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