[SuperZen]

var xhr = new XMLHttpRequest(),
    method = "GET",
    url = "http://localhost:2998/";

  xhr.open(method, url, true);
  xhr.onreadystatechange = function () {
    if (xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
      console.log(this);
    };
  };
  xhr.send();
  xhr.send(); //Uncaught DOMException: Failed to execute 'send' on 'XMLHttpRequest': The object's state must be OPENED.

(function (open) {

    XMLHttpRequest.prototype.open = function (method, url, async, fourth) {
      console.log(fourth)
      this.addEventListener("readystatechange", function () {
        if (this.readyState == 4 && this.status == 200) {
          console.log(this);
        }
      }, false);
      open.call(this, method, url, async, fourth);
    }
  })(xhr.open);

  xhr.open(method, url, true, 'fourth');
  xhr.send();
  xhr.open(method, url, true, 'fourth');
  xhr.send();

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