手写AjaxAJAX async JavaScript and XML(JSON)AJAX async JavaScri

纯记忆性面试题,随便意思一下就好了

(xhr = XMLHttpRequest)
var request = new XMLHttpRequest()

request.open('GET','/XXX')
request.onreadstatechange = function(){
    if(request.readyState === 4){
    if(request.status >=200 && request.status <=300 ||request.status === 304){
        success(request)
    }
    else {fail(request)}
};

request.send('{"name":"XXX"}')

AJAX async JavaScript and XML(JSON)