mock XMLHttpRequest class

mockXMLHttpRequest.js

(function(w){

  if ('NativeXMLHttpRequest' in w) return;

  // Preserve the native XMLHttpRequest class
  w.NativeXMLHttpRequest = w.XMLHttpRequest;

  class XMLHttpRequestEventTarget extends EventTarget {
    constructor() {
      super();

      this.onloadstart = null;
      this.onprogress = null;
      this.onabort = null;
      this.onerror = null;
      this.onload = null;
      this.ontimeout = null;
      this.onloadend = null;
    }
  };

  class XMLHttpRequestUpload extends XMLHttpRequestEventTarget {
    constructor() {
      super();
    }
  }

  class XMLHttpRequest extends XMLHttpRequestEventTarget {
    constructor() {
      super();

      // event handler
      this.onreadystatechange = null;

      // states
      this.readyState = 0;

      // request
      this.timeout = 0;
      this.withCredentials = false;
      this.upload = new XMLHttpRequestUpload;

      // response
      this.responseURL = '';
      this.status = 0;
      this.statusText = '';
      this.responseType = '';
      this.response = '';
      this.responseText = '';
      this.responseXML = null;
    }
  }

  // states
  XMLHttpRequest.prototype.UNSENT = 0;
  XMLHttpRequest.prototype.OPENED = 1;
  XMLHttpRequest.prototype.HEADERS_RECEIVED = 2;
  XMLHttpRequest.prototype.LOADING = 3;
  XMLHttpRequest.prototype.DONE = 4;

  // request
  XMLHttpRequest.prototype.open = function (method, url, async = true, username = null, password = null) {
    console.log('open', arguments);
  };
  XMLHttpRequest.prototype.setRequestHeader = function (name, value) {
    console.log('setRequestHeader', arguments);
  };
  XMLHttpRequest.prototype.send = function (body = null) {
    console.log('send', arguments);
  };
  XMLHttpRequest.prototype.abort = function () {
    console.log('abort', arguments);
  };

  // response
  XMLHttpRequest.prototype.getResponseHeader = function (name) {
    console.log('getResponseHeader', arguments);

    return null;
  };
  XMLHttpRequest.prototype.getAllResponseHeaders = function () {
    return '';
  };
  XMLHttpRequest.prototype.overrideMimeType = function (mime) {
    if (arguments.length < 1) {
      throw new TypeError(`Failed to execute 'overrideMimeType' on 'XMLHttpRequest': 1 argument required, but only 0 present.`);
    }
  };

  w.XMLHttpRequest = XMLHttpRequest;

})(window);

/*

// Revert:

(function(w){

  if ('NativeXMLHttpRequest' in w) {
    w.XMLHttpRequest = w.NativeXMLHttpRequest;
    delete w.NativeXMLHttpRequest;
  }

})(window);

*/