webApi前端ajax调用后端返回{"readyState":0,"status":0,"statusText":"error"}解决方案

 var url = data.url,
            params = data.params,
            try_times = data.try_times ,
            async = data.sync == 'false' ? false : true;      

        $.ajax({
            url: url,
            type: "post",
            timeout: 60000,
            async: async,
            data: json.stringify(params),
            datatype: "text",
            success: function (data) {
                alert("aaaa+bbb");                
            }, error: function (error) {//增加访问出错信息返回
                alert("出错了" + json.stringify(error));               
            }, complete: function (xmlhttprequest, status) {
                
            }
        });

前端报错为：{"readystate":0,"status":0,"statustext":"error"}，这个问题主要是由于跨域引起的

解决方案如下：

在请求的服务端的web.config中添加如下节点:

<system.webserver>   
    <httpprotocol>
      <customheaders>
        <add name="access-control-allow-origin" value="*" />
        <add name="access-control-allow-headers" value="content-type" />
        <add name="access-control-allow-methods" value="get, post, put, delete, options" />
      </customheaders>
    </httpprotocol>
  </system.webserver>