如果条件CSS标记中所述视口低于1100px，如何禁用“external.js”？
<head>
<meta charset="utf-8">
<meta name="viewport" content="initial-scale=1.0, user-scalable=yes, width=device-width">
<link rel="stylesheet" media="screen" href="style/master.css">
<link rel="stylesheet" media="screen" href="style/index.css">
<link rel="stylesheet" media="only screen and (max-width:1100px)" href="style/master1100.css">
<link rel="stylesheet" media="only screen and (max-width:700px)" href="style/master700.css">
</head>
<body>
...
</body>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.1/jquery.min.js"></script>
<script src="scripts/external.js"></script>