resolve-url.ts

import isServer from './is-server';
import querystring from 'querystring';

/**
 * note: encodeURIComponent is available via browser (window) or natively in node.js
 * if you use another js engine for server-side rendering you may not have native encodeURIComponent
 * and would then need to install a package for that functionality
 * @param {Object} params
 */
function getQueryString(params: querystring.ParsedUrlQueryInput) {
  return Object.keys(params)
    .map((k) => `${encodeURIComponent(k)}=${encodeURIComponent(String(params[k]))}`)
    .join('&');
}

/**
 * Resolves a base URL that may contain query string parameters and an additional set of query
 * string parameters into a unified string representation.
 * @param {string} urlBase the base URL that may contain query string parameters
 * @param {Object} params query string parameters
 * @returns a URL string
 * @throws {RangeError} if the provided url is an empty string
 */
function resolveUrl(urlBase: string, params: querystring.ParsedUrlQueryInput = {}): string {
  if (!urlBase) {
    throw new RangeError('url must be a non-empty string');
  }

  // This is a better way to work with URLs since it handles different user input
  // edge cases. This works in Node and all browser except IE11.
  // https://developer.mozilla.org/en-US/docs/Web/API/URL
  // TODO: Verify our browser support requirements.
  if (isServer()) {
    const url = new URL(urlBase);
    for (const key in params) {
      if ({}.hasOwnProperty.call(params, key)) {
        url.searchParams.append(key, String(params[key]));
      }
    }
    const result = url.toString();
    return result;
  }

  const qs = getQueryString(params);
  const result = urlBase.indexOf('?') !== -1 ? `${urlBase}&${qs}` : `${urlBase}?${qs}`;
  return result;
}

export default resolveUrl;