用原生JS对AJAX做简单封装的实例代码

var createAjax = function() { var xhr = null; try { //IE系列浏览器 xhr = new ActiveXObject("microsoft.xmlhttp");
  } catch (e1) { try { //非IE浏览器 xhr = new XMLHttpRequest();
    } catch (e2) { window.alert("您的浏览器不支持ajax，请更换！");
    }
  } return xhr;
}; 

var ajax = function(conf) { // 初始化 //type参数,可选 var type = conf.type; //url参数，必填 var url = conf.url; /https://img.qb5200.com/download-x/data参数可选，只有在post请求时需要 var data = conf.data; /https://img.qb5200.com/download-x/datatype参数可选 var dataType = conf.dataType; //回调函数可选 var success = conf.success; if (type == null){ //type参数可选，默认为get type = "get";
  } if (dataType == null){ /https://img.qb5200.com/download-x/dataType参数可选，默认为text dataType = "text";
  } // 创建ajax引擎对象 var xhr = createAjax(); // 打开 xhr.open(type, url, true); // 发送 if (type == "GET" || type == "get") {
    xhr.send(null);
  } else if (type == "POST" || type == "post") {
    xhr.setRequestHeader("content-type", "application/x-www-form-urlencoded");
    xhr.send(data);
  }
  xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { if(dataType == "text"||dataType=="TEXT") { if (success != null){ //普通文本 success(xhr.responseText);
        }
      }else if(dataType=="xml"||dataType=="XML") { if (success != null){ //接收xml文档 success(xhr.responseXML);
        } 
      }else if(dataType=="json"||dataType=="JSON") { if (success != null){ //将json字符串转换为js对象 success(eval("("+xhr.responseText+")"));
        }
      }
    }
  };
}; 

 ajax({ type:"post",
    url:"test.jsp",
    data:"name=dipoo&info=good",
    dataType:"json",
    success:function(data){ alert(data.name); } });