1）当使用非空ng-app和ng-controller时，变量由angularjs控制器来处理
2）控制器接管模型变量后，直接修改模型，模版里的变量还是会自动变的
<!DOCTYPE html>
<html>
<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.5.8/angular.min.js"></script>
<body>
<p>Try to change the names.</p>
<div ng-app="myApp" ng-controller="myCtrl">
First Name: <input type="text" ng-model="firstName"><br>
Last Name: <input type="text" ng-model="lastName"><br>
<br>
Full Name: {{firstName + " " + lastName}}
</div>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
$scope.firstName= "John";
$scope.lastName= "Doe";
});
</script>
</body>
</html>