function ajax(method, url, data,fn) { //封装为方法
let htp = null; //定义个变量
//判断兼容低版本ie
try {
htp = new XMLHttpRequest()
}
catch (err) {
htp = new ActiveXObject("Microsoft.XMLHTTP")
}
//判断使用get方法传输还是用posh方法传输
if (method == "get") {
htp.open(method, url +"?"+ data);
htp.send()
} else {
htp.open(method, url);
htp.setRequestHeader('content-type', 'application/x-www-form-urlencoded');
htp.send(data)
}
//监听交互事件
htp.onreadystatechange = function () {
//判断传输是否成功
if (htp.readyState == 4 && htp.status == 200) {
fn(htp.responseText)
}
}
}