Simple XHR to use like fetch in REST APIs

simple-xhr.js

var oReq = new XMLHttpRequest()
oReq.onload = function (e) {
  var xhr = e.target
  if (xhr.status === 200 && onSuccess) {
    onSuccess(xhr.response)
  } else if (xhr.status !== 200 && onFailure) {
    onFailure(xhr.response)
  }
}
oReq.open(method, action, true)
oReq.setRequestHeader('Content-Type', 'application/json')
oReq.responseType = 'json'
oReq.send(JSON.stringify(formdata))