waitingInInterval.js

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));

setTimeout(() => console.log('1200ms elapsed'), 1200);

const foo = () => {
    let intervalId;
    const intervalFunction = async() => {
        clearInterval(intervalId); //clear so it will not execute again after 100ms
        console.log('interval executed');
        await sleep(120); //some long action
        return intervalId = setInterval(intervalFunction, 100); //reassign id and start after sleep()
    };
    setInterval(intervalFunction, 100);
};

foo();