用于RESTful web服务的Ajax

Question

我编写了一个Ajax函数，它应该在框架中用于与with服务器交互。

(自写的)可以用于获取文件和文件夹内容，创建文件和文件夹，并删除它们。

/**
 * Performs an Ajax-Request
 * @param  {string}   method            HTTP-Method
 * @param  {string}   url
 * @param  {string}   postData          optional; HTTP-body
 * @param  {string}   contentType       optional; default: "multipart/form-data"
 * @param  {object}   authentication    optional; loginCredentials for basicAuth; {"user": "userName", "password": "password"}
 * @param  {function} callback          optional; called, if the operation succeeded;
 *                                              Parameter: (string) response-body
 * @param  {function} errorCallback     optional; called, if the operation failed;
 *                                              Parameter: 1 = (number) statusCode; (==0, if the given parameters were invalid)
 *                                                         2 = (string) statusText; (or errorMessage, if statusCode == 0)
 */
function ajax(method, url, postData, contentType, authentication, callback, errorCallback) {
    if(typeof(errorCallback) != 'function'){
        errorCallback = function(){};                           //Dummy-function to reduce code
    }

    //Validate the input parameters
        if(["GET", "HEAD", "POST", "PUT", "DELETE"].indexOf(method) < 0){
            return errorCallback(0, "Invalid method");
        }
        if(postData && ["HEAD", "POST"].indexOf(method) < 0){          //Other methods don't support postData
            return errorCallback(0, "Invalid method for postData");
        }
    //Get a cross-browser XML-HTTP-Object:
        var req = createXMLHTTPObject();
        if (!req) {
            return errorCallback(0, "Ajax is not supported");   //Oops! Something bad happened
        }
        req.open(method, url, true);    //async = true
    //Manipulate header-fields:
        //req.setRequestHeader('User-Agent','XMLHTTP/1.0');
        if(postData){
            if(contentType){
                req.setRequestHeader('Content-type', contentType);
            }else{
                req.setRequestHeader('Content-type', 'multipart/form-data');
            }
            //key-value pairs with binary data or big payloads:
            //    multipart/form-data
            //key-value pairs with few non-alphanumerical symbols:
            //    application/x-www-form-urlencoded
            //binary data:
            //    application/octet-stream
        }
        if(authentication){
            req.setRequestHeader("Authorization", "Basic " + btoa(authentication.user + ":" + authentication.password));    //btoa() = encode string to base64
        }
        req.overrideMimeType("text/plain; charset=utf-8");      //The browser must not execute javascript-files, if they're loaded with this method
    //Prepare execution:
        req.onreadystatechange = function () {
            if (req.readyState != 4) {
                return;
            }
            if (req.status != 200 && req.status != 304) {
                return errorCallback(req.status, req.statusText);
            }
            if(typeof(callback) == 'function'){
                callback(req.response);
            }
        }
        if (req.readyState == 4){
            return;
        }
        req.send(postData);
}

createXMLHTTPObject()-Method返回XMLHttpRequest-Object或ActiveXObject-Object以实现跨浏览器兼容性。

整个功能应该是跨浏览器兼容的，但不需要支持旧的浏览器，因为框架本身依赖于HTML5。

代码是基于这个例子的

由于我对HTTP协议不太熟悉，所以我有以下问题：

1. 我是否忘记了框架中可能需要的HTTP/RESTful服务的一个重要部分？
2. 能提高效率吗？
3. 还有其他的缺陷/不一致/可能的改进吗？

Answer 1

对JSONP和CORS的支持是任何现代web框架所必需的。

APIwise，我认为您希望将方法的参数简化为单个对象，类似于jQuery是如何做到的。它提供了一个提供默认设置的机会，并从API的角度简化了它。就目前情况而言，使用它将是痛苦的，因为你需要记住许多论点。一个简单的ajax与您的：

ajax('GET', 'index.html', null, null null function(evt) {
    console.log("Success!")
})

vs jQUery或类似的：

ajax({method:'GET', url:'index.html'}, success:function(evt) {
    console.log("Success!")
})