用promise简单封装一个ajax请求
function ajax({
url,type,data,dataType}){
return new Promise(function(open,err){
var xhr=new XMLHttpRequest();
xhr.onreadystatechange = function() {
if(xhr.readyState === 4 && xhr.status === 200 ) {
if(dataType != undefined && dataType.toLowerCase() == "json") {
var res = JSON.parse(xhr.responseText)
} else {
var res = xhr.responseText;
}
open(res);
}
}
if(type.toLowerCase() == "get" && data != undefined) {
url+="?"+data;
}
xhr.open(type,url,true);
if(type.toLowerCase() == "get") {
xhr.send(null);
} else if(type.toLowerCase() == "post") {
xhr.setRequestHeader("Content-Type","application/X-www-form-urlencoded");
xhr.send(data);
}
})
}