Fetch wih Rxjs

rxjs-zip.js

import { tap } from "rxjs/operators";
import { zip } from "rxjs";

function getUser(id) {
  return fetch(`https://jsonplaceholder.typicode.com/users/${id}`).then(res =>
    res.json()
  );
}

function getPost(userId) {
  return fetch(`https://jsonplaceholder.typicode.com/postss/${userId}`).then(
    res => res.json()
  );
}

function makeConcurrentRequests(userId, postId) {
    zip(getUser(userId), getPost(postId)) // we can pass in promises directly
      .subscribe(
        res => {
          const user = res[0];  // getUser response 
          const post = res[1]; // getPost response
      }
    );
}