PromiseRunSingleThread.js

function test1() {
    const timer = (ms) => {
        return new Promise(resolve => {
            setTimeout(() => {
                resolve();
            }, ms)
        });
    }

    let promises = [timer(4000), timer(2000), timer(3000), timer(1000)];

    Promise.all(promises).then((value) => {
        console.log(value); // log array after 4 seconds
    })
}


function test2() {
    function sleep(ms) {
        var e = new Date().getTime() + ms;
        while (new Date().getTime() <= e) { }
    }

    let promises = [sleep(4000), sleep(2000), sleep(3000), sleep(1000)];

    Promise.all(promises).then((value) => {
        console.log(value); // log array after 10 seconds
    })
}