watch unused computed variable vue code example

Example 1: vue add watcher

vm.$watch('person.name.firstName', function(newValue, oldValue) {
	alert('First name changed from ' + oldValue + ' to ' + newValue + '!');
});

Example 2: vue change input value from console

let el = document.getElementById("id");
el.value = val;
el.dispatchEvent(new Event('input'));