Watching computed properties

Yes, you can setup watcher on computed property, see the fiddle.

Following is the code to set watch on computed property:

const demo = new Vue({
    el: '#demo',

    data() {
        return {
            age: ''
        };
    },

    computed: {
        doubleAge() {
            return 2 * this.age;
        }
    },

    watch: {
        doubleAge(newValue) {
            alert(`yes, computed property changed: ${newValue}`);
        }
    }
});