how can i find computed function call in vue js code example

Example 1: computed vue js

var vm = new Vue({
  el: '#demo',
  data: {
    firstName: 'Foo',
    lastName: 'Bar',
    fullName: 'Foo Bar'
  },
  watch: {
    firstName: function (val) {
      this.fullName = val + ' ' + this.lastName
    },
    lastName: function (val) {
      this.fullName = this.firstName + ' ' + val
    }
  }
})

Example 2: vue add watcher

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