vue monitor data change 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 watch

// in component
methods: {
  reverseMessage: function () {
    return this.message.split('').reverse().join('')
  }
}