Promise & Async/Await Demo

asyncAwait.js

// Async function that checks input for no reason
// and then resolves or rejects the promise depending on the input
async function asyncWin(string) {
    var input = string;
    // Private helper method that displays pointless message
    function _pointless() {
        console.log('We just waited 1.337 seconds for no reason.')
    };
    // Invoke helper method after 1.337 seconds and wait until it is done
    var ok = await new Promise((resolve, reject) => {
        setTimeout(() => { resolve(_pointless()); }, 1337);
    });
    // When ready, resolve or reject the promise
    return new Promise((resolve, reject) => {
        if (input) {
            if (input.length > 5) {
                resolve('input is greater than 5 characters: ' + input);
            } else if (input.length === 5){
                resolve('input is 5 characters: ' + input);
            } else {
                reject('input is less than 5 characters: ' + input);
            };
        } else {
            reject('no input');
        };
    });
};

// Run the async function with proper handling
// .then() fires if resolved
// .catch() fires if rejected
asyncWin()
    .then(x => { console.log('Resolved: ' + x); })
    .catch(err => { console.log('Rejected: ' + err); });