<script src="https://cdn.staticfile.org/angular.js/1.4.6/angular.min.js"></script>

​

<div ng-app="myApp" ng-controller="myCtrl">

   <b>请输入姓名：</b><br>

   <b>姓：</b><input type="text" ng-model="lastName"><br>

   <b>名：</b><input type="text" ng-model="firstName"><br>

   <h1>{{ lastName + " " + firstName }}</h1>

   <h2>{{ getFullName() }}</h2>

   <h2 style='color:red'>{{ fullName }}</h2>

</div>

var app = angular.module('myApp', []);

app.controller('myCtrl', function($scope) {

   $scope.lastName = "";

   $scope.firstName = "";

   $scope.getFullName =function(){  return $scope.lastName + " " + $scope.firstName;}

   //监听lastName的变化，更新fullName

   $scope.$watch('lastName', function() {

      $scope.fullName = $scope.lastName + " " + $scope.firstName;

   });

​

   //监听firstName的变化，更新fullName

   $scope.$watch('firstName', function() {

      $scope.fullName = $scope.lastName + " " + $scope.firstName;

   });

});