如何做序列映射，以便每个映射都等待rxjs中的前一个映射? [英] How to do sequence maps so that each map waits for the previous in rxjs?

问题描述

const source = Rx.Observable.from([1, 2, 3, 4, 5]);
const example = source.map(val => { /* asynchronous logic here*/ })
                      .map(val => { /* asynchronous logic here*/ });
                      .map(val => { /* asynchronous logic here*/ });

如何使每个map等待上一个map的异步执行?

How to make so that each map waits for the asynchrounous execution of the previous map ?

推荐答案

您应使用concatMap而不是map并从其回调中返回Observable:

You should use concatMap instead of map and return Observable from its callback:

const source = Rx.Observable.from([1, 2, 3, 4, 5]);
const example = source
  .concatMap(val => { /* asynchronous logic here*/ })
  .concatMap(val => { /* asynchronous logic here*/ })
  .concatMap(val => { /* asynchronous logic here*/ });

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