Event Loop

async.jsx

// Async should be first priority over callbacks and promises
//
// High level idea:
//   - Avoid .then .catch in promise
//   - Syntatic sugar to make async programming similar to sequential code
const axios = require('axios');
DEFAULT_URL = "https://jsonplaceholder.typicode.com"

async function getUser(id) {
    let resp = await axios.get(`${DEFAULT_URL}/users/${id}`)
    return resp.data
}

async function getUserPosts(id) {
    let resp = await axios.get(`${DEFAULT_URL}/users/${id}/posts`)
    return resp.data
}

async function getUserWithPosts(id) {
    var user = await getUser(id)
    let posts = await getUserPosts(id)
    user.posts = posts
    return user
}

getUserPosts(1)
    .then(user => console.log(user))
    .catch(err => console.err(`Error ${err}`))

event.jsx

// EVENT LOOP
let A = () =>  console.log("Running A...")
let B = () =>  console.log("Running B...")
let C = () =>  console.log("Running C...")

function work() {
    A()
    setTimeout(B, 1000)  // Non-blocking.. added to Event loop. run after 1s
    C()
}
work();

// Expected output:
// $ node event_loop.js
// Running A...
// Running C...
// Running B...

promise.jsx

// BLOG PROMISE - CLEAN CODE
// Avoid "modern" promise hell
const axios = require("axios");
DEFAULT_URL = "https://jsonplaceholder.typicode.com"


let getUser = (userId) => {
  return axios.default.get(`${DEFAULT_URL}/users/${userId}`)
    .then(res => res.data)
}


let getUserPosts = (userId) => {
  return axios.default.get(`${DEFAULT_URL}/users/${userId}/posts`)
    .then(res => res.data)
}

let getPostComments = postId => {
  return axios.default.get(`${DEFAULT_URL}/posts/${postId}/comments`)
    .then(res => res.data)
}

let loadPostComments = post => {
  return getPostComments(post.id)
    .then(comments => {
      post.comments = comments
      return post
    })
}

let getUserWithPosts = (id) => {
  var currUser;
  return getUser(id)
    .then(user => {
      currUser = user;
      return getUserPosts(id)})
    .then(posts => {
      return Promise.all(posts.map(post => loadPostComments(post)))})
    .then(posts => {
      currUser.posts = posts
      return currUser})
}

getUserWithPosts(1)
  .then(user => console.log(user))
  .catch(err => console.log(`Something went wrong ${err}`))