source: Dev/trunk/src/client/dojo/request/handlers.js

define([
        '../json',
        '../_base/kernel',
        '../_base/array',
        '../has',
        '../has!dom?../selector/_loader' // only included for has() qsa tests
], function(JSON, kernel, array, has){
        has.add('activex', typeof ActiveXObject !== 'undefined');
        has.add('dom-parser', function(global){
                return 'DOMParser' in global;
        });

        var handleXML;
        if(has('activex')){
                // GUIDs obtained from http://msdn.microsoft.com/en-us/library/ms757837(VS.85).aspx
                var dp = [
                        'Msxml2.DOMDocument.6.0',
                        'Msxml2.DOMDocument.4.0',
                        'MSXML2.DOMDocument.3.0',
                        'MSXML.DOMDocument' // 2.0
                ];

                handleXML = function(response){
                        var result = response.data;

                        if(result && has('dom-qsa2.1') && !result.querySelectorAll && has('dom-parser')){
                                // http://bugs.dojotoolkit.org/ticket/15631
                                // IE9 supports a CSS3 querySelectorAll implementation, but the DOM implementation 
                                // returned by IE9 xhr.responseXML does not. Manually create the XML DOM to gain 
                                // the fuller-featured implementation and avoid bugs caused by the inconsistency
                                result = new DOMParser().parseFromString(response.text, 'application/xml');
                        }

                        if(!result || !result.documentElement){
                                var text = response.text;
                                array.some(dp, function(p){
                                        try{
                                                var dom = new ActiveXObject(p);
                                                dom.async = false;
                                                dom.loadXML(text);
                                                result = dom;
                                        }catch(e){ return false; }
                                        return true;
                                });
                        }

                        return result;
                };
        }

        var handlers = {
                'javascript': function(response){
                        return kernel.eval(response.text || '');
                },
                'json': function(response){
                        return JSON.parse(response.text || null);
                },
                'xml': handleXML
        };

        function handle(response){
                var handler = handlers[response.options.handleAs];

                response.data = handler ? handler(response) : (response.data || response.text);

                return response;
        }

        handle.register = function(name, handler){
                handlers[name] = handler;
        };

        return handle;
});