Set style change event listener in Javascript

Question

My div looks something like this:

Answer 1

It's possible with MutationObserver, but it's a somewhat odd thing to do:

console.log('Script start');
const div = document.querySelector('div');

const o = new MutationObserver(() => {
  console.log('style changed');
});
o.observe(div, { attributes: true, attributeFilter: ["style"] });

setTimeout(() => {
  div.style.backgroundImage = 'url(https://www.gravatar.com/avatar/34932d3e923ffad9a4a1423e30b1d9fc?s=48&d=identicon&r=PG&f=1)';
}, 500);

xx

It would make a lot more sense for the function that makes the style change to call other functions that need to know that the change happened.