promise-cancellation-bluebird.js

// this is simple 1 file 1 route, 
// app with cancellation of promise with bluebird library
//
// canellation of promise which have interval also stopping interval with onCancel

const express = require('express');
const app = express();
const path = require('path');
const bodyParser = require('body-parser');
const Promise = require('bluebird');

Promise.config({
    warnings: true,
    longStackTraces: true,
    cancellation: true,
    monitoring: true
});

app.use(bodyParser.json());
app.use(express.static(path.join(__dirname, 'public')));

const forFoo = (loopIndex) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log('in loop, index ', loopIndex);
            resolve();
        }, 100)
    });
};

//promise
const foo = () => {
    return new Promise((resolve, reject, onCancel) => {
        let index = 0;
        const intervalId = setInterval(async() => {
            let loopIndex = 2;
            index++;
            console.log('in interval, index: ', index);

            //actuall interval task
            while(loopIndex > 0) {
                await forFoo(loopIndex);
                loopIndex--;
            }

            if(index === 5) {
                clearInterval(intervalId);
                resolve();
            }
        }, 1000);
        onCancel(() => {
             clearInterval(intervalId);
         });
    });
};

//test route here
app.get('/test', async(req, res) => {
    let searchPromise = foo()
        .then(function() {
            console.log('not cancel')
        })
        .catch(function(e) {
            console.log(e);
        })
        .finally(function() {
            // This check is necessary because `.finally` handlers are always called.
            if (!searchPromise.isCancelled()) {
                //hideSpinner();
                console.log('not canceled')
            }
        });

    setTimeout(() => {
        searchPromise.cancel();
    }, 3000);
    res.send('Completed');
});

app.listen(5000, () => {
    console.log('Serwer nasłuchuje na porcie: ', 5000)
});