@atlaskit/global-search/dist/es2019/util/url-utils.js

A cross-product search component (batteries included)

export const addQueryParam = (url, queryName, queryValue) => {
  if (!url || !queryName) {
    return url;
  }

  const urlSplit = url.split('?');
  const queryString = urlSplit.length === 2 ? urlSplit[1] : null;
  const urlWithoutQuery = urlSplit.length > 0 ? urlSplit[0] : '';
  const encodedQueryName = encodeURIComponent(queryName);
  const newQueryItem = `${encodedQueryName}=${encodeURIComponent(queryValue || '')}`; // If url has no existing query strings

  if (!queryString) {
    return `${url}?${newQueryItem}`;
  }

  const existingQueries = queryString.split('&');
  const newQueryString = existingQueries.filter(query => {
    // If the query already exists we will replace it with the new one so we filter it out here
    return !query.startsWith(`${encodedQueryName}=`);
  }).concat(newQueryItem).join('&');
  return `${urlWithoutQuery}?${newQueryString}`;
};