Return Value of Function as items Pattern

6 Responses

1. I’m trying to use this method to attache dynamicly a parameter to a proxy in a model.

   proxy : {
   extraParams : {
   test : (function(){
   return ‘test’;
   }).createDelegate(this)()
   },
   ….

   This cause an error : Uncaught TypeError: undefined is not a function
   Where am I wrong ?

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   1. createDelegate? This function has been removed in Ext 4. Now you would use something like this:

      Ext.Function.bind(function(){alert('Hello World!')}, this)()
      

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2. the difference is scope : in case you need to refer to properties/methods of the class itself (`this`) inside the function.
   also, i think it’s a good practice to NOT use inline functions (closures) this way, but to refer to defined methods of the class, or to ‘helper’ methods.
   correct me if i’m wrong .

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3. I don’t understand what the difference is with

   items:function()
   {
   var items[];
   .
   .
   .
   return items;
   }()

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4. @Lucian

   Exactly! I see that you grasped it fully. You can use same pattern also for items array if you need to.

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5. A good example on how to use this pattern:

   {
        xtype: 'combo'
       ,fieldLabel: 'Combobox field label'
       ,width:186
       ,typeAhead: true
       ,displayField: 'value'
       ,mode: 'local'
       ,value: new Date().format('Y')
       ,triggerAction: 'all'
       ,hideOnSelect:false
       ,emptyText:'Select year...'
       ,store: (function(){
           var years = [];         
           var dt = new Date();
           for(var i=1900; i <= dt.format('Y'); i++){
               years.push(i);
           }    
           return years;
       }).createDelegate(this)()
   }
   
   

   That code will render a combobox for selecting one year between 1900 and the current year, basically an “year selector”.

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