XMLHttpRequest 发送请求步骤

//1.创建XMLhttpRequest对象

var request = new XMLHttpRequest(); 

//2.使用open方法设置和服务器的交互信息 

request.open('get','https://api.muxiaoguo.cn/api/lishijr');

//3.设置requestHeader

request.setRequestHeader('Content-type', 'application/json; charset=utf-8');

//4.发送请求

request.send();

//5.如果请求完成，并响应完成，获取到响应数据

request.onreadystatechange=function (){                
  if(request.readyState === 4&&request.status===200){                    
    console.log(JSON.parse(request.responseText));                    
    }          
  } 
}