mapResultOk

Transforms the success value (Ok) of a Result type emitted by the source. If the value is Ok, the mapping function is applied; if Err, it remains unchanged.

Marble Diagram

mapResultOk(x => x * 2)

Example

//  Timeline:
//
//  result$   Ok(2)      Err("e")   Ok(5)
//  doubled$  Ok(4)      Err("e")   Ok(10)
//
//  Explanation:
//  - mapResultOk transforms the Ok value of Result emissions
//  - Err values pass through unchanged

const result$ = source<Result<number, string>>();

const doubled$ = result$.pipe(mapResultOk((x) => x * 2));

const valueHistory: Result<number, string>[] = [];

doubled$.subscribe((v) => {
    valueHistory.push(v);
});

result$.next(Result.ok(2));

assert.deepStrictEqual(valueHistory, [Result.ok(4)]);

result$.next(Result.err('e'));

assert.deepStrictEqual(valueHistory, [Result.ok(4), Result.err('e')]);

result$.next(Result.ok(5));

assert.deepStrictEqual(valueHistory, [
    Result.ok(4),
    Result.err('e'),
    Result.ok(10),
]);

View source on GitHub