// https://stackoverflow.com/a/901144/1157536
export default function getQueryParam(name: string, url?: string) {
  if (!url) {
    url = window.location.href;
  }
  name = name.replace(/[[\]]/g, "\\$&");
  const regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)");
  const results = regex.exec(url);
  if (!results) {
    return null;
  }
  if (!results[2]) {
    return "";
  }
  return decodeURIComponent(results[2].replace(/\+/g, " "));
}