Function getExtraParamsUrl

src/impression.js:296–323

(win, target)

 * @return {string}
 */
export function getExtraParamsUrl(win, target) {
  // Get an array with extra params that needs to append.
  const url = parseUrlDeprecated(WindowInterface.getLocation(win).href);
  const params = parseQueryString(url.search);
  const appendParams = [];
  for (let i = 0; i < DEFAULT_APPEND_URL_PARAM.length; i++) {
    const param = DEFAULT_APPEND_URL_PARAM[i];
    if (typeof params[param] !== 'undefined') {
      appendParams.push(param);
    }
  }

  // Check if the param already exists
  const additionalUrlParams = target.getAttribute('data-amp-addparams');
  let {href} = target;
  if (additionalUrlParams) {
    href = addParamsToUrl(href, parseQueryString(additionalUrlParams));
  }
  const loc = parseUrlDeprecated(href);
  const existParams = parseQueryString(loc.search);
  for (let i = appendParams.length - 1; i >= 0; i--) {
    const param = appendParams[i];
    if (typeof existParams[param] !== 'undefined') {
      appendParams.splice(i, 1);
    }
  }
  return getQueryParamUrl(appendParams);
}

/**
 * Helper method to convert an query param array to string