手写一个简易版的Ajax

实现简易版本的Ajax

const ajax = (method, url, data, success, fail) => {
  //实例化
  let request = new XMLHttpRequest()
  //初始化
  request.open(method, url);
  //设置状态变化回调处理请求结果
  request.onreadystatechange = function () {
    //4.代表已经下载完成
    if(request.readyState === 4) {
      if(request.status >= 200 && request.status < 300 || request.status === 304) {
        success(request)
      }else{
        fail(request)
      }
    }
  };
  //发送
  request.send();
}

总结 为了方便自己后期查看而总结,大佬就不用看啦. 哈哈哈勿喷.