60.postMessage.md

60. postMessage

Problem

https://bigfrontend.dev/quiz/postMessage

Problem Description

What does the code snippet below output by console.log?

console.log(1);

window.onmessage = () => {
  console.log(2);
};

Promise.resolve().then(() => {
  console.log(3);
});

setTimeout(() => {
  console.log(4);
}, 0);

console.log(5);

window.postMessage('');

console.log(6);

Answer

1
5
6
3
2
4

Reference

https://html.spec.whatwg.org/multipage/web-messaging.html