我什么时候需要在Backbone.js的使用_.bindAll（）？ [英] When do I need to use _.bindAll() in Backbone.js?

问题描述

我学习Backbone.js的，感觉这个困惑：
我下面教程：
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/

，你可以在第一个例子中看到（1.js）：

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，如果我注释掉了一句： _ bindAll（这一点，'渲染'）; ，这仍然可以工作。我曾在谷歌搜索，有人说，该方法 bindAll（）是必要的，因为如果我打开我的背景下，的this.render 可能不可用。我觉得在背景糊涂。也可能有人解释我当主叫（ this.render ）将不可用？

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

有关你给的例子 _ bindAll（这一点，'渲染'）; ISN ŧ必要的，但如果你有回调函数，其中这个都不可能更改为别的东西的情况下，那么 _bindAll（）可以派上用场了。

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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