multipart/form-data：FormData

var formdata = new FormData();
formdata.append("name", "xxx");
formdata.append("appKey", "xxx");
formdata.append("password", "xxx");

var requestOptions = {
  method: 'POST',
  body: formdata,
  redirect: 'follow'
};
fetch("xxxx", requestOptions)
  .then(response => response.json())
  .then(result => console.log(result))
  .catch(error => console.log('error', error));