我什么时候需要在 Backbone.js 中使用 _.bindAll()? [英] When do I need to use _.bindAll() in Backbone.js?
问题描述
我正在学习backbone.js,对此感到困惑:我正在按照教程进行操作:http://arturadib.com/hello-backbonejs/
I am learning backbone.js, and feel confused on this: I am following the tutorial : http://arturadib.com/hello-backbonejs/
如您在第一个示例 (1.js) 中所见:
as you can see in the first example (1.js):
(function($){
var ListView = Backbone.View.extend({
el: $('body'), // attaches `this.el` to an existing element.
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(){
$(this.el).append("<ul> <li>hello world</li> </ul>");
}
});
var listView = new ListView();
})(jQuery);
但是如果我注释掉这句话:_.bindAll(this, 'render');
,这仍然有效.我在谷歌搜索过,有人说 bindAll()
方法是必要的,因为如果我切换上下文,this.render
的调用可能不可用.我对上下文"感到困惑.当调用 (this.render
) 不可用时,有人可以解释一下吗?
But if I comment out the sentence: _.bindAll(this, 'render');
, this will still work. I have searched in google and someone said that the method bindAll()
is necessary since if I switched my context, the calling of this.render
may unavailable. I feel confused on the "context". and also could some one explain me when the calling (this.render
) will unavailable?
推荐答案
对于你给出的例子 _.bindAll(this, 'render');
不是必需的,但如果你有回调函数,其中 this
可以更改为其他内容的上下文,然后 _bindAll()
可以很方便.
For the example you've given _.bindAll(this, 'render');
isn't necessary but if you have callback functions where this
can possibly be changed to the context of something else, then _bindAll()
can be handy.
例如:
initialize: function(){
_.bindAll(this, 'render', 'clickFunc');
},
events: {
'click .someElement': 'clickFunc'
},
clickFunc: function(e) {
/** If you remove the clickFunc from the list of events in bindAll,
'this' will refer to the element that invoked the event.
Adding the clickFunc event in the _.bindAll, ensures that 'this' stays
as the view.
*/
this /** <-- our focal point */
}
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