console.diff(oldObj, newObj)

console-diff.js

// This snippet lets you watch for properties removed from an object
console.diff = (object, id) => {
  let obj = Object.keys(object);
  if (!id) {
    id = "diff" + Date.now();
    console.lastDiffId = id;
  }

	let listener = addEventListener("diffEnd", (e) => {
  	if (id && e.detail.id != id) {
    	return;
    }
  	let newObj = Object.keys(object);
    newObj = newObj.filter((item) => {
    	return !obj.contains(item);
    });

  	console.log(newObj);
   	removeEventListener(listener);
  });
}
console.diffEnd = (id) => {
	if (!id) {
  	id = console.lastDiffId;
  }
	window.dispatchEvent(new CustomEvent("diffEnd", {
  	detail: {id}
  }));
}