When is JavaScript synchronous?

Question

I have been under the impression for that JavaScript was always asynchronous. However, I have learned that there are situations where it is not (ie DOM manipulations). Is

Answer 1

Is synchronous on all cases.

Example of blocking thread with Promises:

  const test = () => new Promise((result, reject) => {
    const time = new Date().getTime() + (3 * 1000);

    console.info('Test start...');

    while (new Date().getTime() < time) {
      // Waiting...
    }

    console.info('Test finish...');
  });

  test()
    .then(() => console.info('Then'))
    .finally(() => console.info('Finally'));

  console.info('Finish!');

The output will be:

Test start...
Test finish...
Finish!