JavaScript Fetch + XMLHttpRequest

JavaScript Fetch.js

const requestURL = 'https://jsonplaceholder.typicode.com/users'

function sendRequest(method, url, body = null) {
  const headers = {
    'Content-Type': 'application/json'
  }

  return fetch(url, {
    method: method,
    body: JSON.stringify(body),
    headers: headers
  }).then(response => {
    if (response.ok) {
      return response.json()
    }

    return response.json().then(error => {
      const e = new Error('Что-то пошло не так')
      e.data = error
      throw e
    })
  })
}

sendRequest('GET', requestURL)
  .then(data => console.log(data))
  .catch(err => console.log(err))

const body = {
  name: 'Vladilen',
  age: 26
}

sendRequest('POST', requestURL, body)
  .then(data => console.log(data))
  .catch(err => console.log(err))

JavaScript XMLHttpRequest.js

const requestURL = 'https://jsonplaceholder.typicode.com/users'

function sendRequest(method, url, body = null) {
  return new Promise((resolve, reject) => {
    const xhr = new XMLHttpRequest()

    xhr.open(method, url)

    xhr.responseType = 'json'
    xhr.setRequestHeader('Content-Type', 'application/json')

    xhr.onload = () => {
      if (xhr.status >= 400) {
        reject(xhr.response)
      } else {
        resolve(xhr.response)
      }
    }

    xhr.onerror = () => {
      reject(xhr.response)
    }

    xhr.send(JSON.stringify(body))
  })
}

sendRequest('GET', requestURL)
  .then(data => console.log(data))
  .catch(err => console.log(err))

const body = {
  name: 'Vladilen',
  age: 26
}

sendRequest('POST', requestURL, body)
  .then(data => console.log(data))
  .catch(err => console.log(err))

---

it doesn't work (