JSDom

fix-one-a.ts

  Object.defineProperty(XMLHttpRequest.prototype, 'onreadystatechange', {
    enumerable: true,
    configurable: true,
    get: function() {
      return this.orsc;
    },
    set: function(f) {
      this.orsc = f;
    }
  });

fix-one-b.ts

const req = new XMLHttpRequest();
req.onreadystatechange = function(){}
const result = !!req.onreadystatechange;

fix-one-full.ts

function canPatchViaPropertyDescriptor() {
  if ((isBrowser || isMix) && !Object.getOwnPropertyDescriptor(HTMLElement.prototype, 'onclick') &&
      typeof Element !== 'undefined') {
    // WebKit https://bugs.webkit.org/show_bug.cgi?id=134364
    // IDL interface attributes are not configurable
    const desc = Object.getOwnPropertyDescriptor(Element.prototype, 'onclick');
    if (desc && !desc.configurable) return false;
  }

  const xhrDesc = Object.getOwnPropertyDescriptor(XMLHttpRequest.prototype, 'onreadystatechange');

  // add enumerable and configurable here because in opera
  // by default XMLHttpRequest.prototype.onreadystatechange is undefined
  // without adding enumerable and configurable will cause onreadystatechange
  // non-configurable
  Object.defineProperty(XMLHttpRequest.prototype, 'onreadystatechange', {
    enumerable: true,
    configurable: true,
    get: function() {
      return this.orsc;
    },
    set: function(f) {
      this.orsc = f;
    }
  });
  const req = new XMLHttpRequest();
  req.onreadystatechange = function(){}
  const result = !!req.onreadystatechange;
  // restore original desc
  Object.defineProperty(XMLHttpRequest.prototype, 'onreadystatechange', xhrDesc || {});
  return result;
};