fetch('https://mywebsite.com/endpoint/', {
  method: 'POST',
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    firstParam: 'yourValue',
    secondParam: 'yourOtherValue',
  })
})

var request = new XMLHttpRequest();
request.open('POST', '/my/url', true);
request.setRequestHeader('Content-Type', 'application/json; charset=UTF-8');
request.send(data);

$.ajax({
    type: 'POST',
    url: '/some/url',
    data: data
  })
  .done(function(result) {
    this.clearForm();
    this.setState({result:result});
  }.bind(this)
  .fail(function(jqXhr) {
    console.log('failed to register');
  });

npm install superagent --save

import request from "../../node_modules/superagent/superagent";

request
.post('http://localhost/userLogin')
.set('Content-Type', 'application/x-www-form-urlencoded')
.send({ username: "username", password: "password" })
.end(function(err, res){
console.log(res.text);
});