CODEWITHSUNDEEP
javascriptfunctiondojocallbackscope
rbarbalho
rbarbalho

Reputation: 41

How to execute my callback function is a custom Dojo module?

I have the code below:

define(["dojo/_base/declare"],function (declare) {
   return declare("tamoio.Map", null, {

     methodA: function(param){
        console.log(param);
        this.methodB('xxx',function(){
          this.methodC(); //it didn't call!
        });
     },

     methodB: function(text, callback){
       alert('do nothing: ' + text);
       callback();
     },

     methodC: function(){
       alert('hello');
     }

   });
});

When I run my application I received the messege:

Uncaught TypeError: Object [object global] has no method 'methodC'

How to do I invoke a internal method in my module?

I'm using Dojo 1.9.1

Best regards,

Renan

Upvotes: 2

Views: 2908

Answers (1)

Default
Default

Reputation: 16518

You are getting this error because your callback function is being executed in the global scope (window), and there is no function called methodC defined. You need to get methodC to execute in the scope of your widget, and there are two ways of doing this:

1.) Take advantage of JavaScript closures:

 methodA: function(param){
   console.log(param);
   var self = this;   // Create a reference to the widget's context.
   this.methodB('xxx',function(){
     self.methodC();  // Use the widget scope in your anonymous function.
   });
 }

2.) Take advantage of the dojo/_base/lang module's hitch method:

 methodA: function(param){
   console.log(param);
   this.methodB('xxx', lang.hitch(this, function(){
     this.methodC(); 
   }));
 }

The hitch method returns a function that will be executed in the context provided, in this case it is this (the widget).

Upvotes: 3

Related Questions