NodeJS Promise example showing basic usage and control flow with: resolve, reject, then, catch & throw.

nodejs-promise-basic-example.js

function isOdd(x) {
    return new Promise((resolve, reject) => {
        if (x == 11) throw new Error('11 is not allowed!');
        if (x % 2) {
            resolve(x.toString() + ' is odd')
        }
        else {
            reject(new Error(x.toString() + ' is even'));
        }
    });
}

function testIsOdd(x) {
    isOdd(x)
        .then((result) => { console.log('then:', result); })
        .catch((error) => { console.log('catch:', error.message); });
}

testIsOdd(9);
testIsOdd(10);
testIsOdd(11);

// output
// then: 9 is odd
// catch: 10 is even
// catch: 11 is not allowed!