SOURCE

const ajax = (method,url,data,success,fail)=>{
    let  request = new XMLHttpRequest()
    request.open(method,url)
    request.onreadystatechange = function(){
        if(request.readyState === 4){
            if(request.status >=200 && request <=300 || request.status == 304){
                success(request)
            }else{
                fail(request)
            }
        }
    }
    request.end()
}