An IIFE which enqueues a promise in a single promise. Ensures promises are executed in the good order

enqueuePromise.ts

/**
 * Delays a `console.log()` for the given time amount.
 * 
 * @param message A message to log.
 * @param duration A delay in seconds.
 */
function delay(message: string, duration: number): Promise<void> {
    return new Promise((resolve) => {
        setTimeout(() => {
            console.log(message);
            resolve();
        }, timeAmount * 1000);
    });
}

/**
 * An IIFE which enqueues a promise in a single promise. Ensures promises are executed in the good order.
 * 
 * @param promise A promise to enqueue.
 */
const enqueuePromise = (() => {
    let queue: Promise<any> | null = null;

    return async (promise?: () => any) => {
        if (!promise) return queue;
        queue = queue ? queue.then(promise) : promise();
        return queue = queue && queue.then(() => queue = null);
    };
})();

// Useless, but works.
enqueuePromise();

// Enqueue two promises.
enqueuePromise(() => delay('promise 1', 3));
enqueuePromise(() => delay('promise 2', 1));

async function awaitExample() {
    // Await for any promise enqueued in the past.
    await enqueuePromise();
    
    // Enqueue two promises.
    enqueuePromise(() => delay('promise 3', 3));
    enqueuePromise(() => delay('promise 4', 1));
    
    // Await for both promises to end.
    await enqueuePromise();

    console.log('All promises done.');
}

awaitExample();

enqueuePromiseWithId.ts

/**
 * Delays a `console.log()` for the given time amount.
 * 
 * @param message A message to log.
 * @param timeAmount A delay in seconds.
 */
function delay(message: string, timeAmount: number): Promise<void> {
    return new Promise((resolve) => {
        setTimeout(() => {
            console.log(message);
            resolve();
        }, timeAmount * 1000);
    });
}

/**
 * A lambda expression.
 */
type Lambda = () => any;

/**
 * A queue id.
 */
type QueueId = string | number;

/**
 * A queue.
 */
type Queue = (promise?: Lambda) => Promise<any>;

/**
 * Returns a queue which joins a promise in a single promise. Ensures promises are executed in the good order.
 */
function makePromiseQueue(): Queue {
    return (() => {
        let queue: Promise<any> | null = null;

        return async (promise?: Lambda) => {
            if (!promise) return queue;
            queue = queue ? queue.then(promise) : promise();
            return queue = queue && queue.then(() => queue = null);
        };
    })();
}

/**
 * Enqueues a promise in the queue.
 */
const enqueuePromise = makePromiseQueue();

/**
 * Enqueues a promise in the queue which has the given ID.
 */
const enqueuePromiseWithId = (() => {
    const queues: {[id in QueueId]: Queue} = {};
    return (id: QueueId) => queues[id] = queues[id] || makePromiseQueue();
})();

// Useless, but just to show that it works.
enqueuePromise();

// Enqueue two promises.
enqueuePromise(() => delay('promise 1', 3));
enqueuePromise(() => delay('promise 2', 1));

async function awaitExample() {
    // Await for any promise enqueued in the past.
    await enqueuePromise();

    // Enqueue two promises.
    enqueuePromise(() => delay('promise 3', 3));
    enqueuePromise(() => delay('promise 4', 1));

    // Await for both promises to end.
    await enqueuePromise();

    console.log('awaitExample() done.');
}

async function awaitWithIdExample() {
    // Enqueue two promises in the first queue (created during the first call).
    enqueuePromiseWithId('queue1')(() => delay('promise A (queue1)', 1));
    enqueuePromiseWithId('queue1')(() => delay('promise B (queue1)', 0));

    // Enqueue two promises in the second queue (created during the first call).
    enqueuePromiseWithId('queue2')(() => delay('promise A (queue2)', 1));
    enqueuePromiseWithId('queue2')(() => delay('promise B (queue2)', 0));

    // Enqueue two promises in the third queue (created during the first call).
    enqueuePromiseWithId('queue3')(() => delay('promise A (queue3)', 6));
    enqueuePromiseWithId('queue3')(() => delay('promise B (queue3)', 4));

    await enqueuePromiseWithId('queue3')();

    console.log('awaitWithIdExample() done.');
}

awaitExample();
awaitWithIdExample();

You can see it in the following TS Playground 😁