increment/decrements events for dijit.form.NumberSpinner

http://stackoverflow.com/questions/10702787/increment-decrements-events-for-dijit-form-numberspinner

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/dojo/1.7.2/dijit/themes/claro/claro.css">
<style type="text/css">
</style>
<div id="spinner" dojoType="MySpinner" value="3">
</div>

JavaScript

require(["dojo/parser", "dijit/form/NumberSpinner"], 
function(parser, Spinner) { 

dojo.declare("MySpinner", [Spinner], {

    zeroValue: 'Never',
    
    adjust: function(/*Object*/ val, /*Number*/ delta){
        arguments[0] = val && val > 0 ? val : 0;
        return this.inherited(arguments);
    },
    
    _getValueAttr: function() {
      var v = this.inherited(arguments);
      return (!v || v <= 0) ? 0 : v;
    },
    
    format: function(/*Number*/ value, /*dojo.number.__FormatOptions*/ constraints){
    	debugger;
      var v = this.inherited(arguments);
      if (v <= 0 || !v) 
         return this.zeroValue;
        
      return v;
    },
    
    isValid: function(/*Boolean*/ isFocused){
        var v = this.get('value');
        if (!v) {
            return true;
        }           
        return this.inherited(arguments);
    }
});  

dojo.ready(function(){
    
  dojo.parser.parse();
  
}); 
     
});