未捕获的TypeError:对象[object global]没有方法

Question

    var resultItemView = Marionette.CompositeView.extend({
        render : function(){            
            google.load("visualization", "1", {packages:["table"], callback: function() {       
                     var self = this;       
                     this._drawVisualization(self);
            }});
        },

       _drawVisualization : function(self){ 
           var data = new google.visualization.DataTable();

            //Here i'm creating data table  ...

            var chart = new google.visualization.LineChart(self.$el.find("#graphDiv"));
            chart.draw(data, null, null);               

       },
       return resultItemView;
   });

在渲染功能正在加载谷歌可视化,并在回调函数中调用drawVisualization.此外,我将"this"对象作为参数传递给此函数.为此,我使用了匿名函数.在drawVisualization函数中,self等于这个"this"对象.但我得到这个错误:"未捕获TypeError:对象[对象全局]没有方法'_drawVisualization'".我究竟做错了什么？我怎么能纠正它？感谢帮助.

Answer 1

你需要把var self = this;呼叫放在外面google.load.

   var resultItemView = Marionette.CompositeView.extend({
        render : function(){     
            var self = this;       
            google.load("visualization", "1", {packages:["table"], callback: function() {       

                     self._drawVisualization(self);
            }});
        },

这是因为您作为回调参数传递的匿名函数google.load将在不指定this上下文的情况下被调用- 因此它将成为全局(窗口)对象.在render函数内部,您将拥有正确的,this并且可以将其存储在变量中self以在回调函数中引用它.

编辑: 此外,如果您这样做,您不再需要将this上下文传递给_drawVisualization方法.完整示例:

    var resultItemView = Marionette.CompositeView.extend({
        render : function(){   
            var self = this;          
            google.load("visualization", "1", {packages:["table"], callback: function() {       
                self._drawVisualization();
            }});
        },

       _drawVisualization : function(){ 
           var data = new google.visualization.DataTable();

            //Here i'm creating data table  ...

            var chart = new google.visualization.LineChart(this.$el.find("#graphDiv"));
            chart.draw(data, null, null);               

       },
       return resultItemView;
   });