AngularJS变量无法显示

1、错误描述

2、错误原因

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript" src="../js/angular.min.js" ></script>
		<script>
			
		</script>
	</head>
	<body>
		<div>
			<input type="text" ng-model="username" placeholder="请输入用户名" /><br>
			{{username}}
		</div>
	</body>
</html>

页面展示的是username变量，没有展示成需要的；由于该变量没有受AngularJS控制，需要添加ng-app

3、解决办法

<!DOCTYPE html>
<html ng-app>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript" src="../js/angular.min.js" ></script>
		<script>
			
		</script>
	</head>
	<body>
		<div>
			<input type="text" ng-model="username" placeholder="请输入用户名" /><br>
			{{username}}
		</div>
	</body>
</html>