纯JavaScript中的Ajax跨域请求

Question

我想在纯javascript ajax中捕获跨域响应，而不是使用jquery或其他外部库。

var xmlhttp, response;

        try
        {
            xmlhttp = new XMLHttpRequest(); 
        } 
        catch(e)
        { 
            try
            { 
                xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
            } 
            catch (e2)
            { 
                try
                {
                    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
                } 
                catch (e) {}
            }
        }
      xmlhttp.onreadystatechange = function()
        {
            if (xmlhttp.readyState==4)
            { 
                if(callback != undefined)
                { 
                   console.log(xmlhttp.responseText);

                }
            }
        }
    url = "http://xxxx.com/layer.php?callback=callRes"
     xmlhttp.open("GET", url, false);
        xmlhttp.setRequestHeader("Content-Type", "application/json,application/javascript,text/javascript");
xmlhttp.send();

我的回应

XMLHttpRequest cannot load 'http://xxxxx/layer.php?action=12&user_full_name=xyz&user_compa…e=xyz&callback=callRes'. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://test.test.com' is therefore not allowed access.
Uncaught NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'http://xxxxx/layer.php?action=12&user_full_name=xyz&user_compa…e=xyz&callback=callRes'. 

花了很多时间和谷歌搜索，但没有找到任何解决方案

建议是最受欢迎的，但不是脚本方法只有纯javascript ajax