如何合并来自一系列运算符的数据，以便订阅 concatMap 也将 output 两组数据？

Question

I have a series of operator chaining that ends with a concatMap which executes a server side query from the

observer.pipe(
    op1(x => x1),
    op2(x1 => x2),
    op3(x2 => x3),
    concatMap(x3 => z)
).subscribe(z => {
    // How do I get x3 here as well?
})

Answer 1

I found the answer. Its a simple operator zip

observer.pipe(
op1(x => x1),
op2(x1 => x2),
op3(x2 => x3),
concatMap(x3 => zip(z, of(x3))
).subscribe(z => {
    // z[0] is z
    // z[1] is x3
})