httpPost

Makes a POST request to the passed URL.

• Use the XMLHttpRequest web API to make a POST request to the given url.
• Set the value of an HTTP request header with setRequestHeader method.
• Handle the onload event, by calling the given callback the responseText.
• Handle the onerror event, by running the provided err function.
• Omit the fourth argument, err, to log errors to the console's error stream by default.

const httpPost = (url, data, callback, err = console.error) => {
  const request = new XMLHttpRequest();
  request.open('POST', url, true);
  request.setRequestHeader('Content-type', 'application/json; charset=utf-8');
  request.onload = () => callback(request.responseText);
  request.onerror = () => err(request);
  request.send(data);
};

const newPost = {
  userId: 1,
  id: 1337,
  title: 'Foo',
  body: 'bar bar bar'
};
const data = JSON.stringify(newPost);
httpPost(
  'https://jsonplaceholder.typicode.com/posts',
  data,
  console.log
); /*
Logs: {
  "userId": 1,
  "id": 1337,
  "title": "Foo",
  "body": "bar bar bar"
}
*/
httpPost(
  'https://jsonplaceholder.typicode.com/posts',
  null, // does not send a body
  console.log
); /*
Logs: {
  "id": 101
}
*/