1_promise_example.js

let allGood = false;

// Define a Promise
// A Promise can be in one of three states:
// - Pending     | hasn't settled to a value yet
// - Fulfilled   | settled successfully  (calling resolve())
// - Rejected    | settled unsuccessfully (calling reject())
let fetchSomeData = new Promise((resolve, reject) => {
    if (!allGood) {
        reject("error fetching data!")
    } else {
        resolve({
            id: 1,
            message: 'nice work!'
        })
    }
})

// Consuming a Promise
fetchSomeData.then(fetchedData => {
    console.log('then:', fetchedData);
}).catch(err => {
    console.error('catch:', err);
})