ajax.js

define(['jquery', 'underscore'], function ($, _) {
    var _hashes = [],
        hashify;

    hashify = function (params) {
        return JSON.stringify(params);
    };

   return function (url, options) {
        var hash,
            xhr;

        // If url is an object, simulate pre-1.5 signature
        if ( typeof url === "object" ) {
            options = url;
            url = options['url'];
        }

        // Force options to be an object
        options = options || {};
        options['method'] = options['method'] || 'GET';
        options['data'] = options['data'] || {};
        options['url'] = url;
        
        hash = hashify(options);
        
        xhr =  $.ajax(url, options).always(function () {
            _hashes = _.without(_hashes, hashify(options));
            console.log(_hashes);
        });

        if (_.contains(_hashes, hash)) {
            return xhr.abort();
        }else{
            _hashes.push(hash);
            return xhr;
        }
   }; 
});