get

fetch(`//xxx.cn/statp/`,{method:'get',mode:'cors'}).then(res =>res.json()) 
  .then(jsn =>{
        console.log('Success:', jsn) 
 }).catch(error => console.error('Error:', error));

post form

let postData = {a:'b'};
fetch('http://data.xxx.com/Admin/Login/login', {
  method: 'POST',
  mode: 'cors',
  credentials: 'include',
  headers: {
    'Content-Type': 'application/x-www-form-urlencoded'
  },
  body: JSON.stringify(postData)
}).then(function(response) {
  console.log(response);
});

post json

fetch(`//xxx.cn/statp/`,{method:'post',mode:'cors'
,headers:{'Content-Type': 'application/json'}
,body:JSON.stringify({
 　　'id':'XXX'
　　})
  ).then(res =>res.json()) 
  .then(jsn =>{
        console.log('Success:', jsn) 
 }).catch(error => console.error('Error:', error));