Function handleClickUrl

src/impression.js:173–211

* Perform the impression request if it has been provided via * the click param in the viewer arguments. Returns a promise. * @param {!Window} win * @return {!Promise}

(win)

 * @return {!Promise}
 */
function handleClickUrl(win) {
  const ampdoc = Services.ampdoc(win.document.documentElement);
  const viewer = Services.viewerForDoc(ampdoc);

  /** @const {?string} */
  const clickUrl = viewer.getParam('click');
  if (!clickUrl) {
    return Promise.resolve();
  }

  if (clickUrl.indexOf('https://') != 0) {
    user().warn(
      'IMPRESSION',
      'click fragment param should start with https://. Found ',
      clickUrl
    );
    return Promise.resolve();
  }

  if (WindowInterface.getLocation(win).hash) {
    // This is typically done using replaceState inside the viewer.
    // If for some reason it failed, get rid of the fragment here to
    // avoid duplicate tracking.
    WindowInterface.getLocation(win).hash = '';
  }

  // TODO(@zhouyx) need test with a real response.
  return ampdoc
    .whenFirstVisible()
    .then(() => {
      return invoke(win, dev().assertString(clickUrl));
    })
    .then((response) => {
      applyResponse(win, response);
    })
    .catch((err) => {
      user().warn('IMPRESSION', 'Error on request clickUrl: ', err);
    });
}

/**
 * Send the url to ad server and wait for its response