Promises and Asynchronous Javascript

loginAPI.js

// login api which accepts username and password and return a promise
// timeout for simulating request time delay
let login = (username, password) => {
    let validUsername = "ifindev";
    let validPassword = "1234567";
    
    return new Promise((resolve, reject) => {
        setTimeout( () => {
            if(username === validUsername && password === validPassword) {
                resolve("login success!");
            } else {
                reject("login failed!");
            }
        } ,5000);
    });
};

// Valid login
login("ifindev", "1234567")
    .then(result => console.log(result))
    .catch(() => console.log("sorry... login failed"));

// Invalid login
login("visitor", "randompw")
    .then(result => console.log(result))
    .catch(() => console.log("sorry... login failed"));

Promise.js

'use strict';

let state = true;

// Create a fake Fetch API request that returns a promise 
let fetch = new Promise((resolve, reject) => {
    setTimeout( () => {
        if(state === true) {
            resolve({
                    name:"ifindev",
                    dream:"React developer"
                });
        } else {
            reject(new Error("error"));
        }
    } ,5000)
});

//then and catch the promise success and error
fetch
  .then(result => console.log(result))
  .catch(err => console.log(err));