Ajax Library

Ajax.js

var Library = {};
Library.toQueryString = function(data){
    if(data){
        var qstring = [];
        for (var key in data){
            qstring.push(encodeURIComponent(key)+"="+encodeURIComponent(data[key]));
        }
        data = qstring.join("&");
        return data;
    }else{
        return null;
    }
}
Library.createXHR = function(url, options){
    var xhr = false;
    if(window.XMLHttpRequest){
        xhr = new XMLHttpRequest;
    } else if (window.ActiveXObject){
        try{
            xhr = new ActiveXObject('Microsoft.XMLHTTP');
        } catch (e){
            xhr = false;
        }
    }
    if(xhr){
        options = options || {};
        options.method = options.method || "GET";
        options.data = Library.toQueryString(options.data) || null;
        if(options.cache == false && options.method.toUpperCase() == 'GET'){
            url = url + "?_="+new Date().getTime();
        }
        xhr.onreadystatechange = function(){
            if(xhr.readyState == 1){
                if(options.before){
                    options.before.call(xhr);
                }
            }
            if((xhr.readyState == 4) && (xhr.status == 200 || xhr.status == 304)){
                var contentType = xhr.getResponseHeader('Content-Type');
                if(options.complete){
                    if(contentType == 'application/json' || contentType == 'application/octet-stream'){
                        options.complete.call(xhr,JSON.parse(xhr.response));
                    }else if (contentType == 'application/xml' || contentType == 'text/xml'){
                        options.complete.call(xhr, xhr.responseXML);
                    }else{
                        options.complete.call(xhr, xhr.responseText);
                    }
                }else{
                    return false;
                }
            }
        };
        xhr.open(options.method,url, true);
    }
    return xhr;
};
Library.ajax = function(url, options){
    var xhr = Library.createXHR(url,options);
    if(xhr){
        xhr.setRequestHeader('X-Requested-with', 'XMLHttpRequest');
        if(options.method.toUpperCase() == 'POST'){
            xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        }
        xhr.send(options.data);
    }
}