How would the event loop work in this situation?

Question

JavaScript

Hello. What if the code gets to await.fetch() and at that moment the interval fires and deletes the array we are going to push data into after the asynchronous operation, we get 'Cannot read property 'push' of undefined'?)

const session = {
    unanswered: [],
    isRedirect: true,
    date: 1545762010253
};

client.on('message', async (msg) => {
    if (session.isRedirect) {
        await fetch(...);
        session.unanswered.push(msg.id);
    } else {
        session.isRedirect = true;
        session.unanswered = [];
        session.date = Date.now() + 60 * 1000;
    }
});

setInterval(() => {
    if (Date.now() > session.date) {
        session.isRedirect = false;
        delete session.unanswered;
    }
}, 100);

Will wrapping the callback in setImmediate() fix this problem and is it a good solution to this problem?
Actually the example is bad and doesn't reflect my problem. It is necessary for me that when one function manipulates over object others did not interfere with it. setImmediate would be fine (as I understand it, it puts the execution of the callback before the interval), but when asynchronous functions are called in on('message') , the execution flow is transferred to the interval and everything is a mess :)

Answer 1

const delay = ms => new Promise(res => setTimeout(res, ms));

const doAfterUnlock = async (session, func, ...args) => {
    while (session.isBlock) {
        // eslint-disable-next-line no-await-in-loop
        await delay(1); // free event loop
    }

    try {
        session.isBlock = true;
        await func(...args);
    } catch (e) {
        console.error(e);
    } finally {
        session.isBlock = false;
    }
};

Answer 2

As a matter of fact, it may not delete the array at all, but, as in the request, set it to empty.

if (Date.now() > session.date) {
    session.isRedirect = false;
    session.unanswered = [];
}

... no, it won't?

Answer 3

Perhaps something like this

const session = {
    unanswered: [],
    isRedirect: true,
    date: 1545762010253
};
const intervalID = null;
const checkSession = () => {
    if (Date.now() > session.date) {
        session.isRedirect = false;
        delete session.unanswered;
    }
};

client.on('message', async (msg) => {
    if (session.isRedirect) {
        сlearInterval(intervalID);
        await fetch(...);
        session.unanswered.push(msg.id);
        intervalID = setInterval(checkSession, 100);
    } else {
        session.isRedirect = true;
        session.unanswered = [];
        session.date = Date.now() + 60 * 1000;
    }
});

intervalID = setInterval(checkSession, 100);