working with function expressions and chaining of promises

index.js

/*
 * working with resolve()
 */
const doSomethingChained = (name) => {
    console.log('1');
    return new Promise((resolve, reject) => setTimeout(() => {console.log(name); resolve();}, 1500, name));
};

doSomethingChained('Alice').then(() => {
    console.log('2');
});
/* => Output:
 * 1
 * Alice
 * 2
 * Task 1: main code
 * Task 2: the setTimeout call create a new task for the event loop
 * We are chaining the two tasks, meaning that we await termination in taks 2 and than continue with resolve() in taks 1 again
 */

/*
 * working reject() (the wrong way)
 */
const doSomethingBadChained = (name) => {
    console.log('1');
    return new Promise((resolve, reject) => setTimeout(() => {console.log(name); reject('Oops, Something Went Wrong!');}, 1500, name));
};

doSomethingBadChained('Alice').then(() => {
    console.log('2');
});
/* => Output:
 * 1
 * Alice
 * Error: UnhandledPromiseRejectionWarning: Error: Oops, Something Went Wrong!
 * we crashed!
 */

/*
 * working reject()
 */
const doSomethingBadChained2 = (name) => {
    console.log('1');
    return new Promise((resolve, reject) => setTimeout(() => {console.log(name); reject(Error('Oops, Something Went Wrong!'));}, 1500, name));
};

doSomethingBadChained2('Alice').catch((err) => {
    console.log(err);
    console.log('2');
});
/* => Output:
 * 1
 * Alice
 * Error: Oops, Something Went Wrong!
    at Timeout.setTimeout [as _onTimeout] (C:\Users\Andre.Landgraf\WebstormProjects\node-party\index.js:53:89)
    at ontimeout (timers.js:486:15)
    at tryOnTimeout (timers.js:317:5)
    at Timer.listOnTimeout (timers.js:277:5)
 * 2
 * Answer: catching the error allows us to continue the process and handle it in an appropriate way (telling the user)
 * Also, returning an actual Error Object allows us to receive the stack trace of the error which will help tracking down the issue.
 */