saiumesh535

async function loginController(){
    try{
        const a = await loginService().
                        catch((error)=> {throw new CustomErrorHandler({code: 101, message:"a failed",error: error})});
        const b = await someUtil().
                    catch((error)=> {throw new CustomErrorHandler({code: 102, message:"b failed",error: error})});
        //someoeeoe
        if(a && b) console.log("no one failed")
    }catch(error){

saiumesh535

// let's code some emitters 
function Emitter(){
    this.events = {};
}

const emtr = new Emitter();

// on function to push events in array 
Emitter.prototype.on = function(type,listener){
    this.events[type] = this.events[type] || [];

saiumesh535

var express = require('express');
var app = express();
const expressjwt = require('express-jwt')
const jsonwebtoken = require('jsonwebtoken');

// this will verify the token before going to actual requested route (middleware)
// except the "/login" route every request needs token in header which will look like "Authorization:Bearer eyJh..........." refer image in story
app.use(expressjwt({secret: "some key"}).unless({path: ['/', '/login']}))

saiumesh535

async function getData(){
  const a = await someFunction().catch((error)=>console.log(error));
  const b = await someOtherFunction().catch((error)=>console.log(error));
  if(a && b ) console.log("some result")
}

saiumesh535

async function check(req, res) {
    try {
        const a = await someOtherFunction();
        const b = await somethingElseFunction();
        res.send("result")
    } catch (error) {
        res.send(error.stack);
    }
}

saiumesh535

async function check(req, res) {
    someOtherFunction().then((a) => {
        somethingElseFunction().then((b) => {
            res.status(200).json({a: a, b: b});
        }).catch((error) => {
            res.send("error");
        })
    }).catch((error) => {
        res.send("error");
    })

saiumesh535

// traditional way of writing code 
const router = require('express').Router();
router.get('/check', check);
module.exports = router;

async function check(req, res) {
    someOtherFunction().then((a) => {
        somethingElseFunction().then((b) => {
            res.status(200).json({a: a, b: b});
        }).catch((error) => {

saiumesh535

/**
 * this class helps us to make http calls
 */

public class HttpCaller {

    private Context context;
    //private ProgressDialog pDialog;
    private HttpProgressDialog httpProgressDialog;

saiumesh535

// source : https://www.npmjs.com/package/jsonwebtoken
// check token information at : https://jwt.io/

const jwt = require('jsonwebtoken');
// secret key 
const secretKey = 'some secret key';

// this is for verifying and creating token middleware 
app.use((req, res, next) => {
    // if the requested URL is login then create token otherwise verify

saiumesh535

// for examples goto https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function

// this function will return a promise
function multiplication(a, b) {
    return new Promise((resolve, reject) => {
        resolve(a * b)
    })
}

// whn you write async before function it allows you to return promise which was being returned from other function