malavsoni

async function produceData() {
  try {
    const result1 = await processResult(); // ProcessResult function returns promise
    const result2 = await processResult(result1);
    const result3 = await processResult(result2);
    return result3;
  } catch (error) {
    return error;
  }
}

malavsoni

const produceData = () => {
  getData()
    .then(result1 => processResult1(result1))
    .then(result2 => processResult2(result2))
    .then(result3 => return(result3))
    .catch (error) => {
      return error
    }
}

malavsoni

firstFunction(args, function() {
  secondFunction(args, function() {
    thirdFunction(args, function() {
      // And so on...
    })
  })
})

malavsoni

// Simple callback function which return results and data
function processData (callback) {
  fetchData(function (err, data) {
    if (err) {
      console.log("An error has occurred. Abort everything!");
      return callback(err);
    }
    data += 1;
    callback(data);
  });

malavsoni

const app = require("express")();

const PORT = process.env.PORT || 3000;

require("./startup/routes")(app); // Reggister routes for different end points
require("./startup/database")();  // Module will establish connection to MongoDB

app.listen(PORT, () => {
  console.log("Listening to " + PORT);
});

malavsoni

const mongoose = require("mongoose");

module.exports = function () {
  const result = mongoose.connect("mongodb://localhost/app", {
    useNewUrlParser: true,
    useUnifiedTopology: true,
  });
  result
    .then((response) => {
      console.log("Connection Established" + response);

malavsoni

const { User, validate } = require("../models/user");
const express = require("express");
const router = express.Router();

router.get("/", async (req, res) => {
  const users = await User.find().sort("firstName");
  res.send(users);
});

router.post("/", async (req, res) => {

malavsoni

const Joi = require("joi");
const mongoose = require("mongoose");

const User = mongoose.model(
  "User",
  new mongoose.Schema({
    firstName: {
      type: String,
      required: true,
      minlength: 5,

malavsoni

{
  "jwtPrivateKey": "app_name_jwtPrivateKey"
}

malavsoni

const jwt = require('jsonwebtoken');
const config = require('config');

module.exports = function (req, res, next) {
  const token = req.header('x-auth-token');
  if (!token) return res.status(401).send('Access denied. No token provided.');

  try {
    const decoded = jwt.verify(token, config.get('jwtPrivateKey'));
    req.user = decoded;