封装ajax函数（不可跨域）

function ajaxFunc(method, url, data, callback, flag) {
//(1)创建ajax对象
var xhr;
if (window.XMLHttpRequest) {
xhr = new XMLHttpRequest();
} else {
xhr = new ActiveXObject(‘Microsoft.XMLHttp‘);
}
//(2)请求方式get||post
method = method.toUpperCase();
if(method == ‘GET‘){
xhr.open(method, url, flag);
xhr.send();
}else if(method == ‘POST‘){
xhr.open(method, url, flag);
xhr.setRequestHeader(‘Content-type‘, ‘application/x-www-form-urlencoded‘);
xhr.send(data);
}
//(3)监听请求数据
xhr.onreadystatechange = function(){
if(xhr.readyState == 4){
if(xhr.status == 200){
callback(xhr.responseText);
}
xhr = null;
}
}
}
//(4)回调函数对数据处理
function callback(requestData){
var obj = JSON.parse(requestData);
}