NodeJS, Promise and "throw"

promise_throw.js

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

function promiseMethod() {
    return Promise.resolve("ok");
}


function good_sync_example() {
    return new Promise((resolve, reject) => {
        throw new Error("Err... no async and that's fine for throw management by Promise");
    });
}

async function good_async_example() {
    await sleep(100);
    throw new Error("Err...");
}

async function bad_example1_fixed() {
    return new Promise(async (resolve, reject) => {
        try {
            await sleep(100);
            throw new Error("Err... ");
        } catch (e) {
            reject(e);
        }
    });
}

function example3WithAsyncPromiseResultThrow() {
    return new Promise(async (resolve, reject) => {
        promiseMethod()
            .then(async res => {
                await sleep(100);
                throw new Error(`oops was ${res} but..`);
            })
            .catch(err =>{
                console.log(`ex3: ${err.message}`);
                reject(err);
            });
    });
}

function bad_async_example1() {
    return new Promise(async (resolve, reject) => {
        await sleep(100);
        throw new Error("Err... Promise 'async' prevents throw management :(");
    });
}

console.log(`# good_sync_example`)
await good_sync_example().catch(err => console.log(`>>>${err.message}`));
console.log(`# good_async_example`)
await good_async_example().catch(err => console.log(`>>>${err.message}`));
console.log(`# bad_example1_fixed`)
await bad_example1_fixed().catch(err => console.log(`>>>${err.message}`));
console.log(`# example3WithAsyncPromiseResultThrow`)
await example3WithAsyncPromiseResultThrow().catch(err => console.log(`>>>${err.message}`));
console.log(`# bad_async_example1`)
await bad_example1().catch(err => console.log(`>>${err.message}`));
console.log(`# end`)

// node --unhandled-rejections=strict promise_throw_draft.js