JavaScript自己封装ajax的js

[javascript]
/** 
* 执行基本ajax请求,返回XMLHttpRequest 
* Ajax.request({ 
* url
* async 是否异步 true(默认) 
* method 请求方式 POST or GET(默认) 
* data 请求参数 (键值对字符串) 
* success 请求成功后响应函数，参数为xhr 
* error 请求失败后响应函数，参数为xhr 
* }); 
*/ www.2cto.com
Ajax = function() { 
 function request(opt) { 
 function fn() { 
 } 
 var url = opt.url || ""; 
 var async = opt.async !== false, method = opt.method || 'GET', data = opt.data 
 || null, success = opt.success || fn, error = opt.failure 
 || fn; 
 method = method.toUpperCase(); 
 if (method == 'GET' && data) { 
 var args = ""; 
 if(typeof data == 'string'){ 
 //alert("string") 
 args = data; 
 }else if(typeof data == 'object'){ 
 //alert("object") 
 var arr = new Array(); 
 for(var k in data){ 
 var v = data[k]; 
 arr.push(k + "=" + v); 
 } 
 args = arr.join("&"); 
 } 
 url += (url.indexOf('?') == -1 ? '?' : '&') + args; 
 data = null; 
 } 
 var xhr = window.XMLHttpRequest ? new XMLHttpRequest() 
 : new ActiveXObject('Microsoft.XMLHTTP'); 
 xhr.onreadystatechange = function() { 
 _onStateChange(xhr, success, error); 
 }; 
 xhr.open(method, url, async); 
 if (method == 'POST') { 
 xhr.setRequestHeader('Content-type', 
 'application/x-www-form-urlencoded;'); 
 } 
 xhr.send(data); 
 return xhr; 
 } 
 function _onStateChange(xhr, success, failure) { 
 if (xhr.readyState == 4) { 
 var s = xhr.status; 
 if (s >= 200 && s < 300) { 
 success(xhr); 
 } else { 
 failure(xhr); 
 } 
 } else { 
 } 
 } 
 return { 
 request : request 
 }; 
}(); 
[javascript] 
 Ajax.request({ 
 url : path + "/report/topn/topn_data.jsp", 
 data : { 
 datatype : datatype 
 }, 
 success : function(xhr) { 
 onData(xhr.responseText); 
 }, 
 error : function(xhr) { 
 
 } 
});