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我正在做一个骨干应用程序的hello世界示例,它只适用于脚本src标记包含在正文中,而不是标题(我在哪里期待他们)。如果我将它们放在标题中,并且执行提醒(el),则表示未定义。但是,如果我在脚本中使用脚本src标记并执行alert(el),则表示object HTMLBodyElement
和hello world示例有效。我还注意到,我正在看的教程有脚本src标签在内部http://arturadib.com/hello-backbonejs/(这是我可以得到它的唯一办法)'body'undefined取决于脚本标记的位置
为什么呢?
不工作
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>hello-backbonejs</title>
<link rel="stylesheet" href="static/style.css">
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.18/jquery-ui.min.js"></script>
<script src="http://ajax.cdnjs.com/ajax/libs/json2/20110223/json2.js"></script>
<script src="http://documentcloud.github.com/underscore/underscore-min.js"></script>
<script src="http://documentcloud.github.com/backbone/backbone-min.js"></script>
<script src="static/backbone.localStorage-min.js"></script>
<script src="app.js"></script>
</head>
<body>
</body>
</html>
作品
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>hello-backbonejs</title>
<link rel="stylesheet" href="static/style.css">
</head>
<body>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.18/jquery-ui.min.js"></script>
<script src="http://ajax.cdnjs.com/ajax/libs/json2/20110223/json2.js"></script>
<script src="http://documentcloud.github.com/underscore/underscore-min.js"></script>
<script src="http://documentcloud.github.com/backbone/backbone-min.js"></script>
<script src="static/backbone.localStorage-min.js"></script>
<script src="app.js"></script>
</body>
</html>
这是JavaScript
(function($){
// **ListView class**: Our main app view.
var ListView = Backbone.View.extend({
el: $('body'), // attaches `this.el` to an existing element.
// `initialize()`: Automatically called upon instantiation. Where you make all types of bindings, _excluding_ UI events, such as clicks, etc.
initialize: function(){
_.bindAll(this, 'render'); // fixes loss of context for 'this' within methods
this.render(); // not all views are self-rendering. This one is.
},
// `render()`: Function in charge of rendering the entire view in `this.el`. Needs to be manually called by the user.
render: function(){
$(this.el).append("<ul> <li>hello world</li> </ul>");
alert(this.el);
}
});
// **listView instance**: Instantiate main app view.
var listView = new ListView();
})(jQuery);